JP2019007072A - Three-dimensional laminated modeling apparatus and radiation position deviation detection method therefor - Google Patents

Abstract

To provide a three-dimensional laminated modeling apparatus capable of forming a highly accurate three-dimensional structure without being affected by the mechanical accuracy of the stage.SOLUTION: The three-dimensional laminated modeling apparatus includes a stage, a reference member, and an electron detector. The stage supports a modeling container accommodating a powder material and changes its height together with the lamination of the powder material to keep the surface position of the powder material at a constant height. The reference member indicates a position in the horizontal direction of the stage by generating a predetermined reflected electron signal with respect to an electron beam set on the stage and focused and scanned on the surface of the powder material. The electron detector detects an electron signal reflected from the reference member.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a three-dimensional layered modeling apparatus that performs modeling by irradiating a powder material with an electron beam, and an irradiation position deviation detection method thereof.

  The three-dimensional additive manufacturing apparatus irradiates the surface of the powder material with an energy beam such as an electron beam, melts and solidifies a region of a predetermined shape to form a cross-sectional layer, and stacks the cross-sectional layers in a three-dimensional manner. Model the structure.

  The modeled object is stored in a modeling container together with the powder material, and is supported by a stage provided at the bottom of the modeling container. The stage is movable in the vertical direction (Z direction). And when laminating the cross-sectional layers of the modeling object, modeling is performed while keeping the height of the surface of the powder material constant by lowering the stage in the Z direction by the height of the thickness of the powder material to be deposited.

Japanese Patent Laying-Open No. 2015-151666 JP2015-157420A

  In conventional three-dimensional additive manufacturing equipment, unintentional displacement occurs in the horizontal position of the stage due to mechanical precision limitations of the stage feed mechanism and the tilt of the movement axis of the stage feed mechanism, and the irradiation position is There was a risk of deviation.

  Therefore, there is a problem that the accuracy of the three-dimensional structure is limited by the mechanical accuracy of the stage.

  According to one aspect of the following disclosure, a stage that supports the powder material accommodated in the modeling container and maintains the surface position of the powder material at a constant height by changing the height together with the lamination of the powder material; A reference member that indicates a deviation amount of an irradiation position on the surface of the powder material by generating a predetermined reflected electron signal with respect to an electron beam that is placed on the stage and scanned by focusing on the surface of the powder material; There is provided a three-dimensional additive manufacturing apparatus comprising: an electron detector that detects a reflected electron signal reflected from the reference member.

  Further, according to the above aspect, there is provided an irradiation position deviation detection method for a three-dimensional additive manufacturing apparatus, the step of focusing the electron beam on the surface of the powder material, and the reference member using an electron beam aligned with the surface of the powder material Detecting the reflected electrons while scanning, detecting the position of the reference member at the position of the surface of the powder material from the change in the detected amount of the reflected electrons, the initial position of the reference member, and the reference member And a step of detecting a deviation amount of the irradiation position on the surface of the powder material from the difference between the detected value and the position of the irradiation position.

  According to the three-dimensional additive manufacturing apparatus of the above aspect, by using the reference member, it is possible to detect the amount of deviation of the irradiation position at the height of the surface of the powder material caused by the position deviation or inclination of the stage.

  If this irradiation position deviation value is obtained, the irradiation position of the electron beam can be corrected, and a three-dimensional structure can be formed with high accuracy without being restricted by the mechanical accuracy of the stage.

  The summary of the present invention does not enumerate all the features essential to the present invention. A sub-combination of these feature groups can also be an invention.

FIG. 1 is a diagram illustrating a configuration example of a three-dimensional additive manufacturing apparatus 100 according to the first embodiment. FIG. 2 is a plan view illustrating an example of arrangement positions of the modeling container 73, the reference member 90, the calibration mark 67, and the powder supply unit 64. FIG. FIG. 3 is a cross-sectional view showing the modeling container 73, the reference member 90, and the calibration mark 67 of FIG. 2 along the line AA. FIG. 4 is a perspective view showing the positional relationship between the reference member 90 and the electron detector 15. FIG. 5 is an enlarged sectional view showing the vicinity of the knife edge of the reference member 90 of FIG. FIG. 6 is a perspective view showing an example of a scanning method for scanning an electron beam substantially parallel to the Y-axis direction with respect to the knife edge 91 of the reference member 90 of FIG. FIG. 7 is a diagram showing a relationship between an irradiation position of an electron beam scanned in the Y direction in FIG. 6 and a reflected electron signal. FIG. 8 is a diagram illustrating an example of a method for detecting the maximum value of the change rate of the reflected electron signal and the reference position (knife edge position) of the reference member 90 based on the maximum value. FIG. 9 is a flowchart showing the operation of the three-dimensional additive manufacturing apparatus 100 of FIG. FIG. 10 is a flowchart showing a method for measuring the irradiation position deviation due to the stage movement of FIG. 9 and correcting the irradiation position of the electron beam. FIG. 11 is a perspective view of the reference member 190 according to the second embodiment.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

(First embodiment)
FIG. 1 is a diagram illustrating a configuration example of a three-dimensional additive manufacturing apparatus 100 according to the embodiment, and FIG. 2 is a constituent member of the three-dimensional additive manufacturing apparatus 100, which is a modeling container 73, a reference member 90, and a calibration mark 67. And it is a top view which shows the example of the arrangement position of the powder supply part 64. FIG.

  The three-dimensional layered modeling apparatus 100 includes an electron beam column 200, a modeling unit 300, and a control unit 400.

  An electron beam EB is output from the electron beam column 200 of the three-dimensional additive manufacturing apparatus 100. The electron beam EB is controlled by a control signal output from the control unit 400 and is irradiated onto a predetermined range of the surface 63 of the powder layer 62 installed in the modeling unit 300.

  The powder layer 62 is made of, for example, a metal material powder, and is melted and solidified by irradiation with an electron beam EB to form a cross-sectional layer 65. The three-dimensional structure 66 is formed by laminating the cross-sectional layers 65.

  The electron beam column 200 is provided with an electron source 12 that outputs an electron beam EB. The electron source 12 generates electrons by the action of heat or an electric field. Electrons generated from the electron source 12 are accelerated in the −Z direction at a predetermined acceleration voltage (for example, 60 KV) and output as an electron beam EB along the optical axis C. There may be a plurality of electron sources 12.

  The electron beam EB output from the electron source 12 in this way is converged by the electromagnetic lens 13. The electromagnetic lens 13 is composed of, for example, a plurality of electromagnetic coils wound around the electron beam column 200, and sets the lens strength of the electromagnetic lens 13 by flowing a current controlled by the control unit 400. When performing modeling, the electron beam EB is controlled so as to always converge at the height of the surface 63 of the powder layer 62 based on the lens strength set in advance according to the irradiation position.

  The electron beam EB converged by the electromagnetic lens 13 is deflected by the electromagnetic deflector 14 and applied to a predetermined irradiation position. The electromagnetic deflector 14 includes two sets of deflection coils for deflection in the X direction and the Y direction. The controller 400 sets the irradiation position of the electron beam EB by setting the magnitude of the current flowing through these deflection coils.

  The control unit 400 sets the irradiation position of the electron beam on the surface 63 of the powder layer 62 based on the modeling data. Then, current is output to the two sets of deflection coils related to the deflection in the X direction and the Y direction of the electromagnetic deflector 14, and the portion of the cross-sectional layer 65 is scanned while being irradiated with the electron beam EB.

  The modeling unit 300 includes a modeling container 73 that stores a powder material. The modeling container 73 includes a stage 72 and a side wall 73a, and a powder material is supplied from a powder supply unit 64 to a portion surrounded by the side wall 73a. As shown in FIG. 2, the powder supply unit 64 reciprocates within a predetermined movable range by a drive unit 64a that is driven in the X direction, for example. The powder material is flattened by the scraping operation of the powder supply unit 64 to form a powder layer 62 substantially parallel to the upper surface of the stage 72. The upper surface of the powder layer 62 that is irradiated with the electron beam is referred to as a surface 63.

  The height of the stage 72 is movable in the Z-axis direction by the drive unit 77 and the drive rod 76. The height of the stage 72 in the Z-axis direction is set so as to be a constant height when the surface 63 of the powder layer 62 covering the three-dimensional structure 66 is irradiated with the electron beam EB.

  A part of the powder layer 62 melted and solidified by the electron beam irradiation forms a cross-sectional layer 65 and is laminated on the three-dimensional structure 66. The powder layer 62 other than the cross-sectional layer 65 to be laminated is accumulated as a powder material around the three-dimensional structure 66.

  A heater 78 is provided around the modeling container 73. By heating the powder material and the three-dimensional structure 66 to a predetermined temperature below the melting point of the powder material, the deformation of the three-dimensional structure 66 due to thermal strain is reduced. Prevent loss of accuracy.

  A calibration mark 67 is provided around the upper end of the modeling container 73. This calibration mark 67 indicates the position of the edge of the modeling container 73, is used for setting the deflection range of the electromagnetic deflector 14 and calibrating the irradiation position.

  A plurality of electron detectors 15 are provided at the bottom of the electron beam column 200. The electron detector 15 detects the reflected electrons reflected from the calibration mark 67 for determining the deflection range. The electron detector 15 is also used for detecting the position of the stage 72 by a reference member 90 described later.

  The internal space of the electron beam column 200 through which the electron beam EB passes and the space near the surface of the powder layer 62 irradiated by the electron beam EB are evacuated to a predetermined degree of vacuum. This is because the electron beam EB loses energy by colliding with gas molecules in the atmosphere. The three-dimensional additive manufacturing apparatus 100 includes an exhaust unit 80 for exhausting the passage path of the electron beam EB.

  3 is a cross-sectional view of the modeling container 73, the reference member 90, and the calibration mark 67 cut along the line AA in FIG.

  The reference member 90 outputs a predetermined reflected signal by scanning the side portion with the electron beam EB, and indicates the reference position at the height of the surface of the powder material. The reference position in the height of the surface of the powder material reflects the positional deviation and inclination of the stage 72, and can be used for detecting the deviation amount of the irradiation position.

  Hereinafter, the structure of the reference member 90 of this embodiment and its installation part will be described.

  As shown in FIG. 2, a reference member 90 is installed on a portion of the stage 72 that does not interfere with the powder supply unit 64. Although not particularly limited, in the present embodiment, the reference member 90 is installed outside the side wall 73 a of the modeling container 73.

  As shown in FIG. 3, the stage 72 includes a modeling object support 72 a that forms the bottom of the portion surrounded by the side wall 73 a of the modeling container 73, and a reference member installation unit 72 b that is positioned outside the side wall 73 a of the modeling container 73. The modeling object support part 72a and the reference member installation part 72b are integrally connected via a support column 76 that is branched below the stage 72. In addition, when not distinguishing the modeling object support part 72a and the reference member installation part 72b, both will be called the stage 72 collectively. The modeled object support part 72a and the reference member installation part 72b are parallel and formed at the same height.

The modeling object support part 72a contacts the side wall 73a of the modeling container 73 through the seal member 74a. Further, the reference member installation portion 72b contacts the side wall 73a of the modeling container 73 and the side wall 73b of the modeling unit via the seal member 74b. The seal member 74a and the seal member 74b are seal members that prevent metal powder and air from leaking between the stage 72 and the side walls 73a and 73b. Further, the stage 72 is in contact with the side walls 73a and 73b via the seal members 74a and 74b, so that the movement of the stage 72 in the lateral direction (X direction and Y direction) is restricted.
In this manner, the stage 72 moves in the vertical direction (Z direction) while being supported by the side walls 73a and 73b via the seal members 74a and 74b.

  However, backlash due to mechanical accuracy between the stage 72 and the side walls 73a and 73b or a decrease in accuracy due to thermal expansion may occur, and the stage 72 may be displaced or tilted during modeling.

  When such a positional deviation or inclination of the stage 72 occurs, a positional deviation in the XY plane direction occurs in the cross-sectional layer 65 that is formed at the height of the powder layer 62 and is a part of the three-dimensional structure 66, A step may appear on the surface of the three-dimensional structure 66, or the modeled object 66 may be inclined in accordance with the inclination of the stage 72. As described above, the conventional three-dimensional additive manufacturing apparatus has a problem that the accuracy of the three-dimensional structure is restricted by the mechanical accuracy of the stage 72.

  Therefore, in the present embodiment, in order to prevent the accuracy of the model 66 from being lowered due to the positional deviation or inclination of the stage 72, the deviation of the irradiation position at the surface position 63 of the powder layer 62 using the reference member 90 fixed to the upper surface of the stage 72. Detect the amount.

  The reference member 90 having a predetermined shape is fixed to the upper surface of the reference member installation portion 72b that is a part of the stage 72, and moves integrally with the stage 72 in the Z-axis direction. If the stage 72 is displaced and tilted, the reference member 90 is displaced in the XY in-plane direction at the height of the surface 63 of the powder layer 62 due to the influence. The three-dimensional additive manufacturing apparatus 100 measures the XY direction position (referred to as a reference position) of a predetermined structure of the reference member 90 using the electron beam EB at the same height in the Z-axis direction as the surface 63 of the powder layer 62. . Then, the above-described positional shift amount due to the positional shift and tilt of the stage 72 is detected as a shift amount of the irradiation position of the electron beam.

  The length of the reference member 90 is longer than the movable range of the stage 72 so that the upper end of the reference member 90 is positioned higher than the surface of the powder layer 62 even when the stage 72 is lowered most. As an example of the structure of the reference member 90 that outputs a characteristic reflected electron signal when scanned with the electron beam EB focused on the surface of the powder layer 62, a knife edge 91 (see FIG. 4) is formed.

  Accordingly, by scanning the side portion of the reference member 90 extending above the height of the powder layer 62 with the electron beam EB, the reference position corresponding to the case where the upper surface of the stage 72 is moved in the Z-axis direction is detected. it can.

  Thus, since the upper end of the reference member 90 is higher than the powder layer 62, the side portion of the reference member 90 always appears regardless of the amount by which the stage 72 is lowered, and regardless of the change in the height of the stage 72. In addition, it is possible to detect the displacement of the irradiation position of the electron beam due to the displacement and inclination of the stage 72.

  The knife edge 91 of the reference member 90 only needs to extend upward at a predetermined angle with respect to the surface of the stage 72. This is because the reference member 90 having a predetermined shape has a predetermined edge position depending on the height from the surface of the stage 72. In the following specification, a case where the reference member 90 has a knife edge 91 extending perpendicularly to the surface of the stage 72 will be described.

  FIG. 4 is a perspective view showing the reference member 90 and the electron detector 15.

  The reference member 90 shown in FIG. 4 is formed as a triangular prism, and is fixed in a direction perpendicular to the upper surface of the stage 72. There are three planes parallel to the Z direction on the side of the reference member 90, and these planes are in contact with each other at an acute angle or a right angle. In the present embodiment, any one of the sides in contact with these planes is used as a marker for indicating the reference position as the knife edge 91.

  The knife edge 91 of the reference member 90 is formed as a side sandwiched between the side surface 91a and the side surface 91b. The reference member 90 is positioned and fixed so that the knife edge 91 coincides with the reference coordinates (X0, Y0) set as a reference for the position in the horizontal direction (XY direction) set on the stage 72.

  As shown in the figure, the knife edge 91 of the reference member 90 is arranged to face the optical axis C of the electron beam EB so as to output a characteristic reflected electron signal when scanned with the electron beam EB. Note that the center of the angle forming the knife edge 91 does not necessarily have to face the optical axis C of the electron beam EB.

  Further, the direction of the reference member 90 is such that, when the vicinity of the knife edge 91 is irradiated with the electron beam EB, the two side surfaces 91a and 91b adjacent to the knife edge 91 can be irradiated with the electron beam EB, and the electron detector It is preferable that the side surfaces 91 a and 91 b as viewed from 15 are arranged in a direction not hidden behind the knife edge 91.

  Since many of the reflected electrons are emitted in a direction opposite to the incident direction of the electron beam EB, the electron detector 15 is preferably arranged in a direction facing the knife edge 91 of the reference member 90 as shown. Thus, a characteristic intensity change that occurs in the reflected electric signal when the electron beam EB crosses the knife edge 91 can be detected by the electron detector 15, which is suitable for detecting the position of the knife edge 91.

  FIG. 5 is a cross-sectional view showing the reference member 90 of FIG. 4 along the XY plane and enlarging the vicinity of the tip of the knife edge 91.

  The tip of the knife edge 91 does not necessarily have to be formed like a sharp cutting edge, and as shown in FIG. 5, it is formed as a flat tip 91d having a width narrower than the beam diameter at the focal position of the electron beam EB. Also good. Even in the case of such a shape, the influence on the reflected electron signal is small, but the knife edge 91 is not easily damaged, which is preferable.

  Although not particularly limited, the width of the flat portion 91d can be, for example, about 50 μm or less. In addition, it is preferable that the opening angle between the two side surfaces 91a and 91b adjacent to the knife edge 91 is 90 degrees or less. By setting such an angle condition, the intensity change when the electron beam EB is irradiated so as to cross the knife edge 91 appears clearly, and the detection accuracy of the reference position can be improved.

  A plurality of reference members 90 may be provided on the stage 72 at a distance. By providing a plurality of reference members 90, it is possible to detect a more complicated displacement of the irradiation position including local distortion and contraction / expansion.

  Note that the reference member 90 is not limited to the triangular prism as shown in FIG. 4, and may have a quadrangular or polygonal prism shape as long as a knife edge appears.

  Hereinafter, a method for detecting the position of the knife edge 91 on the surface of the powder layer 62 will be described.

  6 is a perspective view showing a method of detecting the reference position by the knife edge 91 of the reference member 90 of FIG. 4, and FIG. 7 shows the change in the intensity of the reflected electron signal of the reference member 90 accompanying the scanning of the electron beam EB. FIG.

  The detection of the reference position by the knife edge 91 is performed before the cross-sectional layer 65 is formed by irradiating the powder layer 62 with the electron beam EB, thereby detecting the positional deviation or inclination of the stage 72 in the planar direction.

  For this purpose, among the knife edges 91 of the reference member 90, the position coordinates in the X direction and the Y direction of the knife edge 91 at the position where the position in the height direction (Z direction) coincides with the height of the surface 63 of the powder layer 62 are obtained. It is required to detect.

  Therefore, in this embodiment, prior to the scanning of the knife edge 91, the focal position of the electron beam EB is adjusted to the height of the surface 63 of the powder layer 62.

  Next, the electron beam EB is scanned around the knife edge 91 as shown in FIG. In the illustrated example, an example in which the reference position is detected using the knife edge 91 facing the X direction of the reference member 90 will be described, but the present invention is not limited to this.

  A surface indicated by a broken line indicates a surface having the same height as the surface 63 of the powder layer 62 that is the focal position of the electron beam EB. The electron beam EB scans in a state where the position of the surface 63 is always focused.

  In the case of the illustrated example, the electron beam EB is continuously moved in the + Y direction, scanned across the knife edge 91, and then moved in the −X direction or the + X direction by a predetermined feed distance ΔX. Thereafter, the electron beam EB is continuously scanned in the −Y direction to move across the knife edge 91.

  The above scanning is repeated while moving a plurality of times in the X direction.

  In one scan, the intensity of the reflected electrons emitted from the reference member 90 changes according to the angle formed by the electron detector 15 and the side surfaces 91a and 91b of the reference member 90. In the scanning, the intensity of the reflected electrons changes greatly when the electron beam EB passes through the knife edge 91.

  When scanning is performed at the position indicated by P1 in the drawing, the electron detector 15 first detects the reflected electrons emitted from the front side surface 91a in the drawing as the irradiation position of the electron beam EB is moved. . Thereafter, reflected electrons emitted from the inner surface 91b through the knife edge 91 are detected by the electron detector 15 (see FIG. 4). At the knife edge 91, a large intensity change occurs in the reflected electrons when the electron beam EB passes through.

  As a result, a reflected electric signal as indicated by reference numeral P1 in FIG. 7 is obtained.

  In FIG. 7, the intensity change of the reflected electron signal also becomes gradual at the scanning position in the X direction at the symbol P <b> 1. This is because, as shown in FIG. 6, the electron beam EB scanned along the symbol P1 is out of the focal position at the position crossing the knife edge 91, and the periphery of the knife edge 91 is irradiated by the relatively wide electron beam EB. It is to be done. That is, the electron detector 15 detects the reflected electrons from the front surface 91a and the reflected electrons from the back surface 91b in FIG. As a result, as shown by the curve P1 in FIG. 7, the intensity change of the reflected electron signal when passing through the knife edge 91 changes gently in a range corresponding to the diameter of the irradiation spot of the electron beam EB. When the focal point of the electron beam EB deviates from the surface position 63 at a position passing through the knife edge 91 as in the scanning position P1, the diameter of the irradiation spot becomes relatively large, and the intensity change of the reflected electron signal changes. Becomes moderate.

  In FIG. 6, the same applies to the scanning of the electron beam EB at the position of the reference symbol P2 out of the focal position, and the intensity change of the reflected electron signal of the reference symbol P2 in FIG.

  On the other hand, at the scanning position indicated by reference symbol P0 in FIG. 6, the position of the knife edge 91 and the position of the surface 63, which is the focal position of the electron beam EB, coincide. At this time, the diameter of the irradiation spot of the electron beam EB when passing through the knife edge 91 is very small. The intensity change of the reflected electron signal when passing through the knife edge 91 occurs in a very narrow range. Therefore, as shown in the reflected electron signal denoted by reference symbol P0 in FIG.

  By detecting the scanning position in the X direction where the reflected electron signal with the steepest intensity change of the reflected electron signal is obtained, the reference position coordinate X0 in the X direction of the knife edge 91 of the reference member 90 at the height of the powder layer 62 is obtained. It can be detected. Further, the reference position coordinate Y0 in the Y direction can be detected from the irradiation position in the Y direction in which the rate of change of the reflected electron signal denoted by reference symbol P0 in FIG.

  FIG. 8 is a diagram illustrating a method for detecting the maximum value of the change rate of the reflected electron signal and the position of the knife edge 91 of the reference member 90 based on the maximum value.

  In the present embodiment, the absolute value of the change rate of the reflected electron signal for each scanning position in the X direction is obtained. Then, as shown in FIG. 8, an approximate curve representing the relationship between the maximum absolute value of the rate of change of the reflected electron signal and the scanning position of the electron beam EB in the X direction is obtained. From the position indicating the maximum value of the approximate curve, the coordinate X0 of the reference position, which is the X coordinate of the knife edge 91 at the position of the surface 63 of the powder layer 62, can be obtained accurately.

  Similarly, with respect to the scanning position in the Y direction, an approximate curve representing the relationship between the maximum absolute value of the rate of change of the reflected electron signal and the scanning position in the Y direction of the electron beam EB is obtained. The coordinate Y0 of the reference position, which is the Y coordinate of the knife edge 91 at the position of the surface 63 of the powder layer 62, can be accurately obtained from the position indicating the maximum value of the approximate curve.

  Further, by obtaining the difference between the coordinates (X0, Y0) of the reference position obtained by the above method and the initial value of the reference position on the stage 72, the deviation amount of the irradiation position at the position of the surface 63 of the powder layer 62 is obtained. Is obtained. Here, the initial value of the reference position on the stage 72 is the knife edge 91 at the height of the powder layer 62 when the stage 72 moves parallel to the Z-axis direction without causing any positional displacement and inclination in the XY directions. It corresponds to the position coordinates. The initial value of the reference position is obtained in advance based on the shape of the reference member 90 and the direction of the knife edge 91 fixed to the upper surface of the stage 72, and is initially set in the control unit 400.

  Hereinafter, the operation of the additive manufacturing apparatus 100 will be described.

  FIG. 9 is a flowchart showing the operation of the additive manufacturing apparatus 100.

  The additive manufacturing apparatus 100 calibrates the electron beam EB prior to modeling the three-dimensional structure 66 (step S510).

  The calibration of the electron beam EB adjusts the lens strength of the electromagnetic lens 13 of the electron beam EB so as to adjust the focal position, and also aligns the electron beam EB. The alignment of the electron beam EB is performed by inputting a control signal to the deflector 14 to deflect the electron beam EB and detecting the calibration mark 67. Based on the result, the relationship between the input value to the deflector 14 and the irradiation position of the electron beam is calibrated to align the electron beam EB.

  Next, the height of the stage 72 is adjusted under the control of the control unit 400 (step S520). Here, the drive unit 77 is driven to move the stage 72 in the −Z direction by the height of the single powder layer 62.

  Thereafter, the powder layer 62 is supplied to the modeling container 73 (step S530). The powder material is supplied to the upper side of the stage 72 while being flattened by the scraping operation of the powder supply unit 64, thereby forming a powder layer 62 substantially parallel to the stage 72.

  Next, the deviation of the irradiation position is measured, and the three-dimensional additive manufacturing apparatus 100 corrects the irradiation position of the electron beam EB (step S540). The stage 72 may move in the −Z direction in step S520, thereby causing a positional shift or an inclination in the XY direction.

  Therefore, in this embodiment, the irradiation position shift due to the movement of the stage 72 in the −Z direction is measured by the method described with reference to FIGS. 5 to 7 to correct the irradiation position.

  Hereinafter, specific measurement of deviation of the irradiation position and correction of the irradiation position will be described.

  FIG. 10 is a flowchart showing the operation of measuring the irradiation position shift and correcting the irradiation position (step S540 in FIG. 9) in the three-dimensional additive manufacturing apparatus 100.

  First, in step S541, the three-dimensional additive manufacturing apparatus 100 scans the reference member 90 with the electron beam EB. That is, the electron beam EB is deflected in a state where the focal position of the electron beam EB is aligned with the surface of the powder layer 62, and the knife edge 91 that is the target portion of the reference member 90 is scanned. Here, as shown in FIG. 6, a predetermined range crossing the knife edge 91 to be detected is set as a scanning range, and the range is scanned with the electron beam EB.

  Next, the process proceeds to step S542, and the backscattered electrons generated by scanning with the electron beam EB are detected by the electron detector 15. The intensity of the reflected electrons, which is the detection result of the electron detector 15, is stored in the storage unit in the control unit 400 as a reflected electron signal in association with the irradiation position of the electron beam EB.

  Next, in step S543, the control unit 400 detects the position of the knife edge 91 that is the reference position. Here, the change rate of the detected electron intensity of the reflected electron signal is obtained by the method described with reference to FIGS. 7 and 8, and the position of the knife edge 91 is detected from the position where the change rate shows the maximum value.

  Next, in step S544, the control unit 400 determines the amount of irradiation position deviation caused by the movement of the stage 72 in the -Z direction. That is, the control unit 400 obtains a difference between the initially set reference position coordinates of the reference member 90 (initial position of the reference member) and the position coordinates of the knife edge 91 detected in step S543, so that the stage 72 An irradiation position deviation amount (ΔX, ΔY) due to the position deviation and the inclination is calculated.

  Thereafter, in step S545, the control unit 400 corrects the irradiation position of the electron beam EB. Here, the irradiation position of the electron beam EB is corrected by adding the irradiation position deviation (ΔX, ΔY) calculated in step S544 to the coordinate value of the irradiation data stored in the control unit 400.

  Thus, the correction of the irradiation position of the electron beam EB in step S540 in FIG. 9 is completed.

  Next, the process proceeds to step S550 in FIG. 9, and the three-dimensional additive manufacturing apparatus 100 melts and solidifies the powder layer 62 by irradiating the surface 63 of the powder layer 62 with the electron beam EB based on the corrected irradiation data. Thereby, the cross-sectional layer 65 is formed, and modeling for one layer of a three-dimensional structure is completed.

  Thereafter, in step S560, the three-dimensional additive manufacturing apparatus 100 determines whether the formation of all layers has been completed. In step S560, when the three-dimensional layered modeling apparatus 100 determines that the modeling of all layers is not completed, the process returns to step S520 to model the next layer.

  On the other hand, if the three-dimensional additive manufacturing apparatus 100 determines in step S560 that the formation of all layers has been completed, the modeling operation is terminated.

  As described above, prior to irradiation with the electron beam EB, the three-dimensional additive manufacturing apparatus 100 detects the amount of misalignment due to the movement of the stage 72 and the amount of misalignment of the irradiation position due to the tilt, and corrects the irradiation position.

  Thereby, according to the three-dimensional additive manufacturing apparatus 100 of this embodiment, a highly accurate molded article can be modeled exceeding the restriction | limiting of the mechanical precision of the stage 72. FIG.

(Second Embodiment)
FIG. 11 is a perspective view of the reference member 190 according to the second embodiment.

  A reference member 190 shown in FIG. 11 is installed on the stage 72 in the same manner as the reference member 90 (see FIG. 3) of the first embodiment.

  The reference member 190 of the present embodiment includes a plurality of flat portions having different heights in the Z direction, and these are arranged in a step shape. In the illustrated example, the reference member 190 has a flat portion 92 having a height of Z1, a flat portion 94 having a height of Z2 provided at a higher position, and a flat portion having a height of Z3 provided at a higher position. Three flat portions with the portion 96 are provided.

  Positioning mark patterns 92a, 94a, 96a are provided at the centers of the flat portions 92, 94, 96, respectively.

  The reference member 190 is formed of a conductor such as metal, and the mark patterns 92a, 94a, and 96a are formed, for example, as patterns in which grooves having a width and a depth of about several tens of μm are engraved in a cross shape. By scanning the mark patterns 92a, 94a, and 96a with the electron beam EB, reference positions by the flat portions 92, 94, and 96 are obtained, respectively.

  The amount of displacement of the irradiation position of the electron beam EB with respect to the heights Z1, Z2 and Z3 in the Z-axis direction is detected before the operation of laminating and forming the three-dimensional structure 66 by melting and solidifying the powder layer 62. The stage 72 is moved to the heights of the patterns 92a, 94a, and 96a, and the positions of the mark patterns 92a, 94a, and 96a in the XY directions are detected by electron beams at the respective heights. That is, the detection of the displacement amount of the irradiation position of the electron beam EB is performed immediately after the calibration of the electron beam EB (step S510) is completed in the flowchart of FIG.

  In the present embodiment, by properly using the mark position detection results of the mark patterns 92a, 94a, and 96a in accordance with the height of the stage 72, the amount of irradiation position deviation can be reduced even when the movement of the stage 72 in the Z direction is large. Can be corrected.

  When the position in the Z direction on the upper surface of the stage 72 is included in the movement range from the initial height 0 to −Z1, the position coordinates of the mark pattern 92a registered in advance and the mark pattern actually measured are measured. The irradiation position is corrected by detecting the amount of deviation of the irradiation position from the difference from the measured value of 92a.

  In the control unit 400, the position coordinates (X1, Y1) of the mark pattern 92a set according to the installation position of the reference member 190 may be stored in advance as initial values. From the difference between the position coordinates (X1, Y1) and the measured value of the position coordinates of the mark pattern 92a after the stage 72 is moved down, the deviation amount of the irradiation position to be corrected is obtained.

  For the range where the position of the stage 72 is -Z1 to -Z2, the amount of deviation of the irradiation position is measured using the mark pattern 94a of the flat portion 94 of the reference member 190.

  Further, for the range where the position of the stage 72 is in the range of −Z2 to −Z3, the irradiation position shift amount is measured using the mark pattern 96a of the flat portion 96 of the reference member 190.

  As described above, in the reference member 190 of the present embodiment, the stage 72 that moves greatly in the Z direction by using a plurality of flat portions having different heights and selectively using the mark pattern for each predetermined height range of the stage 72. Even so, it is possible to detect the deviation of the irradiation range and correct the irradiation range.

DESCRIPTION OF SYMBOLS 12 ... Electron source, 13 ... Electromagnetic lens, 14 ... Deflector, 15 ... Electron detector, 62 ... Powder layer, 63 ... Surface position (focal position), 64 ... Powder supply part, 65 ... Cross-section layer, 66 ... Three-dimensional Structure, 67 ... Calibration mark, 72 ... Stage, 72a ... Modeling object support part, 72b ... Reference member installation part, 73 ... Modeling container, 73a, 73b ... Side wall, 74, 74a, 74b ... Seal member, 76 ... Drive rod , 77... Drive unit, 78... Heater, 90, 190... Reference member, 91... Knife edge, 91 a, 91 b .. Side surface, 91 d ... Tip, 92, 94, 96. .

Claims (10)

A stage for supporting the powder material contained in the modeling container and maintaining the surface position of the powder material at a constant height by changing the height together with the lamination of the powder material;
A reference member that indicates a deviation amount of an irradiation position on the surface of the powder material by generating a predetermined reflected electron signal with respect to an electron beam that is placed on the stage and scanned by focusing on the surface of the powder material;
An electron detector for detecting a reflected electron signal reflected from the reference member;
A three-dimensional additive manufacturing apparatus comprising:   The three-dimensional additive manufacturing apparatus according to claim 1, wherein the reference member has a knife edge extending upward at a predetermined angle with respect to the surface of the stage.   The three-dimensional additive manufacturing apparatus according to claim 2, wherein the reference member extends to a position higher than the surface of the powder material.   The three-dimensional additive manufacturing apparatus according to claim 3, wherein the reference member is formed in a prismatic shape extending upward from the stage.   The three-dimensional additive manufacturing according to claim 1, wherein the reference member includes a plurality of flat portions having different heights, and each flat portion is provided with a mark pattern indicating the position of the stage. apparatus.   The three-dimensional additive manufacturing apparatus according to claim 5, wherein the reference member has the plurality of flat portions arranged stepwise.   The three-dimensional additive manufacturing apparatus according to claim 1, wherein a plurality of the reference members are arranged on the stage. A stage for supporting the powder material stored in the modeling container and maintaining the surface position of the powder material at a constant height by changing the height together with the lamination of the powder material, and the powder material installed on the stage. A reference member that indicates a deviation amount of an irradiation position on the surface of the powder material by generating a predetermined reflected electron signal with respect to the electron beam scanned while being focused on the surface, and a reflected electron reflected from the reference member An electronic detector for detecting, an irradiation position deviation detection method of a three-dimensional additive manufacturing apparatus comprising:
Focusing the electron beam on the surface of the powder material;
Detecting reflected electrons while scanning the reference member with an electron beam matched to the surface of the powder material;
Detecting the position of the reference member at the position of the surface of the powder material from a change in the detection amount of the reflected electrons;
Detecting a deviation amount of an irradiation position on the surface of the powder material from a difference between a detection value of an initial position of the reference member and a position of the reference member;
A method for detecting an irradiation position shift of a three-dimensional additive manufacturing apparatus, comprising: The reference member is formed in a prismatic shape extending upward from the stage,
The irradiation position shift detection method of the three-dimensional additive manufacturing apparatus according to claim 8, wherein reflected electrons are detected by scanning the vicinity of a knife edge which is a side of the prism with the electron beam. The detection of the horizontal position of the stage is obtained by scanning a plurality of times while changing the position of the electron beam to obtain a plurality of reflected electron intensity changes when crossing the knife edge of the reference member, and
Detecting the irradiation position of the electron beam that maximizes the rate of change of the reflected electron intensity as the position of the reference member at the height of the surface of the powder material;
The irradiation position shift detection method of the three-dimensional additive manufacturing apparatus according to claim 9, wherein

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