Patent Application
20210154741
This application claims priority to Japanese Application No. 2019-163854 filed Sep. 9, 2019, the disclosure of which is hereby incorporated by reference in its entirety.
The present invention relates to a three-dimensional powder bed fusion additive manufacturing (PBF-AM) method and a three-dimensional PBF-AM apparatus for shaping an object by depositing layers of thinly spread powder samples on a layer-by-layer basis.
In recent years, a three-dimensional PBF-AM technology, by which a thinly spread powder sample is deposited layer on layer (hereinafter referred to as a “powder layer”), has been attracting attention and many types of three-dimensional PBF-AM technologies that differ in material of a powder sample and in shaping method have been developed (see JP 2019-7065 A, for example).
The three-dimensional PBF-AM apparatus disclosed in JP 2019-7065 A thinly spreads a powder sample on a flat base plate 5. Then, the three-dimensional PBF-AM apparatus causes the powder sample to melt and coagulate (solidify) by irradiating a portion to be shaped in the powder layer made up of a thinly spread powder sample with a laser beam or electron beam serving as a heat source and having a narrowed beam diameter.
A solidified area in the powder layer corresponds to a cross section of a three-dimensional shaped object represented by three-dimensional CAD data, sliced along a plane perpendicular to the stacking direction. The three-dimensional PBF-AM apparatus disclosed in JP 2019-7065 A repeats the process of moving the base plate in the height direction of the shaped object, spreading the powder sample, and causing a predetermined area of the powder layer to melt and solidify. As a result, a three-dimensional structural object in which thinly sliced objects are layered is shaped.
However, the three-dimensional PBF-AM apparatus disclosed in JP 2019-7065 A proceeds with the shaping process irrespective of whether a shaping surface has any abnormality after a predetermined area of the powder layer is melted and solidified (after melting), with the result that a shaped object may be completed with an abnormality included.
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a three-dimensional PBF-AM method and a three-dimensional PBF-AM apparatus that suppress the occurrence of a defect in a shaped object.
According to one aspect of the present invention, a squeegeeing step, a main melting step, and a shaping surface checking step are included. In the squeegeeing step, a powder supply unit supplies a powder sample onto a base plate to stack powder layers. In the main melting step, a beam generation unit irradiates a powder bed which is a top layer of the powder layers with an electron beam to melt a two-dimensional shape area, which is a single layer obtained by slicing a shaping model. In the shaping surface checking step, a detection unit detects a backscattered electron that is generated when the area melted in the main melting step is irradiated with an electron beam generated by a beam generation unit and it is determined whether the melting state is normal. When it is determined in the shaping surface checking step that the melting state is not normal, a re-melting step is performed to re-irradiate the area melted in the main melting step with an electron beam generated by the beam generation unit.
According to one aspect of the present invention, a shaping surface is checked after a predetermined area of a powder layer is melted, and therefore the occurrence of a defect in the shaped object can be suppressed.
Example embodiments of the present invention will now be described with reference to the accompanying drawings. Note that components common in the drawings are denoted by the same reference numerals and duplicate descriptions are omitted.
[Configuration of Three-Dimensional PBF-AM Apparatus]
In
As illustrated in
The build box 3 includes a table 3a to which a metal powder 8 is supplied and a tube 3b being continuous with the table 3a. The table 3a is formed in a rectangular plate shape whose both ends with respect to the X direction are in contact with the inner wall of the vacuum chamber 1, and a through hole is created in the center of the table 3a. The tube 3b is formed in a tubular shape along the perimeter of the through hole in the table 3a, and one end of the tube 3b is continuous with the lower surface of the table 3a. That is, in the case where the through hole in the table 3a is circular, the tube 3b is formed in a cylindrical shape that is set to have an inner diameter substantially equal to the diameter of the through hole.
The build box fixing unit 4 is formed in a tubular shape having a tube hole communicating with the tube hole of the tube 3b. The build box 3 (the tube 3b) is fixed to one end of the build box fixing unit 4 with respect to the axial direction, and the other end of the build box fixing unit 4 with respect to the axial direction is fixed to the bottom surface of the vacuum chamber 1. The tube 3b of the build box 3 together with the build box fixing unit 4 form a pit, which is a space for shaping a shaped object 9.
Inside the pit, the powder platform 6 and a Z drive mechanism 5 (an example of a drive unit) for moving the powder platform 6 along the Z direction are provided. The powder platform 6 is formed in a plate shape contoured in accordance with the shape of the tube hole of the tube 3b. That is, in the case where the tube hole of the tube 3b is circular, the powder platform 6 is formed into a circular disc. In addition, a seal member 7 is attached to the lateral perimeter surface of the powder platform 6.
The seal member 7 is interposed between the powder platform 6 and the inner perimeter surface of the tube 3b to seal the gap between the powder platform 6 and the inner perimeter surface of the tube 3b so that the powder (metal powder 8) is prevented from falling from the gap. The seal member 7 is slidably in contact with the inner perimeter surface of the tube 3b. As the Z drive mechanism 5, a rack and pinion or a ball screw, for example, can be employed. The atmosphere inside the vacuum chamber 1 is evacuated by a vacuum pump (not illustrated), and the inside of the vacuum chamber 1 is held with a vacuum.
Above the build box 3, two powder tanks 11, a dispenser 12 connected to the bottom of the powder tank 11, a squeegee arm 13, and a blade 14 attached to the squeegee arm 13 are provided. The powder tank 11, the dispenser 12, the squeegee arm 13, and the blade 14 represent an example of a powder supply unit according to the present invention.
The two powder tanks 11 face each other across the through hole (pit) in the table 3a. The two powder tanks 11 are each loaded with the metal powder 8. Note that the type of the metal powder loaded therein may be different between the two powder tanks 11. The dispenser 12 supplies a predetermined amount of the metal powder 8 onto the table 3a of the build box 3 from the metal powder 8 loaded in the powder tank 11.
As illustrated in
The blade 14 is attached to a lower portion of the squeegee arm 13. The blade 14 flattens the metal powder 8 supplied onto the table 3a through reciprocating movement of the squeegee arm 13 between the two powder tanks 11. During the process, the metal powder 8 is spread over the powder platform 6 whose position have the same height as that of the metal powder 8 on the table 3a.
In addition, a base plate 10 is disposed in the metal powder 8 on the powder platform 6. The base plate 10 is a base on which the shaped object 9 is to be formed through layering. Note that, when the base plate 10 is heated during shaping, the metal powder 8 serves as a heat insulating layer to inhibit the heat from transferring from the base plate 10 to the build box 3 and to the powder platform 6.
Below the electron gun 2, two-segmented detectors 16A and 16B (an example of the detection unit) are disposed. The two-segmented detectors 16A and 16B are fixed at positions where the detectors do not interfere with the squeegee arm 13.
As illustrated in
In the present embodiment, to check an observed surface (for example, a shaping surface of the shaped object 9), an area slightly smaller than the base plate 10 is scanned with a precisely focused electron beam to collect backscattered electron images. The electron beam is generated with an emission current being low and enough to detect a backscattered electron (for example, about 1 mA). Note that the focus may be changed by using a preset method by which shaping recipe data is stored in advance or by using an autofocus function that is used in an electron microscope and the like and involves collecting backscattered electron images a plurality of times.
Current amplifiers 17 are respectively connected to the two-segmented detectors 16A and 16B, and a signal A and a signal B, which are outputs from the respective current amplifiers 17, are transmitted to the shaping control device 60 (see
That is, since a backscattered electron in the specular reflection direction has a greater intensity, in the case where an observed surface (for example, a shaping surface) has irregularities, a signal difference dependent on the inclination angle of the surface of irregularities is caused between the backscattered electrons incident on the two-segmented detectors 16A and 16B. Therefore, from the result of calculating A−B or (A−B)/(A+B), information corresponding to irregularities can be imaged (a backscattered electron image can be obtained). The shaping control device 60 determines that irregularities have been created on a shaping surface if the height of a concave or convex portion exceeds a predetermined threshold.
As shown in
Furthermore, a more accurate concave-convex shape can be obtained by additionally performing similar detection in the Y direction (using four-segmented detectors). In the case of dividing “A−B” by “A+B”, A−B can be less affected by fluctuations in a primary beam current or by changes in an image of emitted backscattered electrons depending on the condition of a shaping surface. In addition, in the case of dividing “A−B” by “A+B”, the linearity of the change with respect to the beam scanning is improved as compared with A−B.
Examples of the detector may include a pn junction type semiconductor detector used in an electron microscope. In the three-dimensional PBF-AM apparatus based on an electron beam system, the irradiating electron beam currents are of the order of mA, and thus a backscattered electron may be directly detected as a current with a metal plate electrode. Using a current amplifier capable of applying a voltage of about −100 V to the detector makes it possible to avoid the influence of scattered electrons of about 100 eV.
The three-dimensional PBF-AM apparatus 50 includes the shaping control device 60, which is electrically connected to the vacuum chamber 1. The shaping control device 60 includes a read only memory (ROM) 62, a random access memory (RAM) 63, a central processing unit (CPU) 64, a Z drive control unit 65, a powder supply drive control unit 66, and an electron gun drive control unit 67.
The shaping control device 60 transmits and receives information in accordance with a predetermined format to and from the individual drive units in the three-dimensional PBF-AM apparatus 50 via a communication interface (not illustrated). For example, a serial interface is used as the communication interface.
The ROM 62 is a non-volatile storage unit that stores a shaping program to be executed by the CPU 64, parameters of the shaped object 9, and the like. The RAM 63 is a volatile storage unit that temporarily stores data and is used as a work area. Note that the shaping program and data including parameters of the shaped object 9 as stored in the ROM 62 may be stored in a non-volatile mass storage device.
The CPU 64 reads the shaping program stored in the ROM 62 into the RAM 63 to control the processing and operations of each unit in accordance with the shaping program. The CPU 64 is connected to the individual units via a system bus 69 so that data can be transmitted and/or received to/from the units. The CPU 64, the ROM 62, and the RAM 63 are examples of a control unit.
The Z drive control unit 65 controls operations of the Z drive mechanism 5 under the control of the CPU 64. The powder supply drive control unit 66 controls operations of the dispenser 12 and the squeegee arms 13 under the control of the CPU 64. The electron gun drive control unit 67 controls, under the control of the CPU 64, the intensity and the irradiation position of an electron beam emitted from the electron gun 2.
A basic three-dimensional PBF-AM process according to the present embodiment will now be described.
The three-dimensional PBF-AM process begins with a base plate heating step.
In the base plate heating step, the electron gun drive control unit 67 (see
Specifically, an area slightly smaller than the entire upper surface of the base plate 10 is irradiated with the electron beam 21 by scanning the area with the electron beam 21. Then, the base plate 10 is kept heated in advance to a temperature at which the metal powder 8 to be spread later is preliminarily sintered. In this step, the upper surface of the base plate 10 is irradiated and scanned with the electron beam 21 being not focused but defocused (having a larger beam diameter), thereby avoiding locally melting the base plate 10.
When the temperature of the base plate 10 has risen, the metal powder 8 around the base plate 10 is preliminarily sintered to become a preliminary sintered body.
Next, a squeegeeing step is performed in the three-dimensional PBF-AM process.
In the squeegeeing step, first, the Z drive control unit 65 (see
Then, the powder supply drive control unit 66 (see
Next, a preliminary sintering step is performed in the three-dimensional PBF-AM process.
In the preliminary sintering step, the metal powder 8 that has been spread in the squeegeeing step becomes the preliminary sintered body 22 (see
Next, a powder heating step is performed in the three-dimensional PBF-AM process.
In the powder heating step, the electron gun drive control unit 67 (see
Next, a powder bed checking step is performed in the three-dimensional PBF-AM process.
In the powder bed checking step, the electron gun drive control unit 67 (see
Immediately after the powder heating step is finished, the powder bed in a normal state is fully covered with the powder because the powder has been squeegeed, and no bulk (melted) surface of the shaped object 9 is exposed. Therefore, no irregularity is created on the powder bed. In contrast, when, for example, a bulk (melted) surface of the shaped object 9 is exposed from the powder bed or a stepped shape is created between the shaped object 9 and its surroundings because of insufficient supply of the metal powder 8, the powder bed will have irregularities.
When it is confirmed from the acquired backscattered electron image that no irregularity is created on the powder bed (that is, the powder bed is fully covered with the powder), the CPU 64 determines that the powder bed is normal. When the CPU 64 determines that the powder bed is normal, the processing goes to the next main melting step.
On the other hand, when it is confirmed from the acquired backscattered electron image that irregularities are created on the powder bed, the CPU 64 determines that an abnormality has occurred in the powder bed. When the CPU 64 determines that an abnormality has occurred in the powder bed, the squeegeeing step is performed again, and then the powder heating step is performed again. That is, when the CPU 64 determines that an abnormality has occurred in the powder bed, the process of shaping the current layer is carried out again from the squeegeeing step.
Note that, when it is determined that an abnormality has occurred in the powder bed and the temperature of the powder bed is lower than a predetermined temperature, a process similar to the powder heating step is performed to heat the powder bed prior to returning to the squeegeeing step.
Alternatively, it may be determined whether an abnormality has occurred in the powder bed in the powder bed checking step by comparing a backscattered electron image acquired in the shaping surface checking step described later (a backscattered electron image before the squeegeeing step) with a backscattered electron image acquired in the powder bed checking step (a backscattered electron image after the squeegeeing step). For example, if there is no difference between backscattered electron images before and after the squeegeeing step (if the images are identical), which means that the powder bed is not fully covered with powder, the CPU 64 determines that an abnormality has occurred in the powder bed.
On the other hand, if there is a difference between backscattered electron images before and after the squeegeeing step, it is checked whether the difference between the two exists in an area including a shaping surface. Then, if the difference between the two exists in the entire area including a shaping surface, the CPU 64 determines that the powder bed is normal. On the other hand, if the difference between the two does not exist in the entire area including a shaping surface, which means that a shaping surface may be exposed from part of the powder bed, the CPU 64 determines that an abnormality has occurred in the powder bed.
Next, a main melting step is performed in the three-dimensional PBF-AM process.
In the main melting step, the electron gun drive control unit 67 (see
Next, a shaping surface checking step is performed in the three-dimensional PBF-AM process.
In the shaping surface checking step, the electron gun drive control unit 67 (see
The CPU 64 determines that irregularities have been created on the shaping surface if the height of a concave or convex portion exceeds a predetermined threshold. Furthermore, in accordance with the condition of the area of irregularities, the CPU 64 determines whether the area has been overmelted or has not been melted (including insufficient melting). For example, if the area formed with irregularities is relatively smooth, the CPU 64 determines that the area has been overmelted and has been coagulated with its melted surface waving. In contrast, if an unmelted powder remains in the area of irregularities that are relatively sharp-edged, the CPU 64 determines that the area has not been melted.
When the CPU 64 determines that irregularities are created on a shaping surface (that is, the shaping surface is not in a normal melted state) in the shaping surface checking step, the main melting step is performed again (this step is hereinafter referred to as a “re-melting step”). In this case, when the temperature of the shaping surface is lower than a certain temperature, a process similar to the powder heating step is performed to heat the shaping surface, and then the re-melting step is carried out.
In the re-melting step performed in the case of overmelting, the electron gun drive control unit 67 (see
After the re-melting step, the shaping surface checking step is performed. Note that the re-melting step and the shaping surface checking step are repeated until the CPU 64 determines that no irregularity is created on the shaping surface (that is, the shaping surface is in a normal melted state) in the shaping surface checking step. Alternatively, when the number of times the shaping surface checking step is performed for shaping the current layer has reached a predetermined number, the CPU 64 may determine that an error related to the melting has occurred and the three-dimensional PBF-AM process may be stopped. After the CPU 64 determines that no irregularity is created on the shaping surface (that is, the shaping surface is in a normal melted state) in the shaping surface checking step, a subsequent heating step is performed as described below.
Next, a subsequent heating step is performed in the three-dimensional PBF-AM process.
In the subsequent heating step, the electron gun drive control unit 67 (see
After the subsequent heating step is finished, the processing returns to the squeegeeing step for the next layer to repeat the squeegeeing step, the preliminary sintering step, the powder heating step, the powder bed checking step, the main melting step, the shaping surface checking step, and the subsequent heating step. When the subsequent heating step for the last layer of the shaped object is finished, the three-dimensional PBF-AM process is ended. As a result, the main melted portions (melts) are stacked layer by layer to form the shaped object 9.
As described above, in the first embodiment, the powder bed is checked for irregularities after the powder heating step is finished, and if irregularities are found, it is determined that an abnormality has occurred in the powder bed. Then, the squeegeeing step and the powder heating step are performed again. Accordingly, the main melting step is allowed to be performed on the powder bed in a normal state. As a result, the occurrence of a defect in the shaped object 9 can be suppressed.
In addition, the shaping surface is checked for irregularities after the main melting step is finished, and if irregularities are found on the shaping surface, the re-melting step is performed. Thus, the processing is prevented from going to the next step in the state where an abnormality has occurred on the shaping surface. As a result, the occurrence of a defect in the shaped object 9 can be suppressed.
In the first embodiment described above, the two-segmented detectors 16A and 16B are used to detect irregularities on the powder bed and on the shaping surface. However, a shaped object on the powder bed (melting area) can be identified by using a single electron detector, as in the case of acquiring usual backscattered electron images.
The contrast obtained from backscattered electrons is dependent on the density (atomic number) of the observed object irradiated with an electron beam. That is, a substance having a higher density (higher atomic number) emits a larger number of backscattered electrons, and thus provides a brighter backscattered electron image. Accordingly, when a single electron detector is used, a shaped object (melted bulk) also looks brighter than a preliminary sintered body in a backscattered electron image obtained from the detection result. Therefore, the above-described powder bed checking step can still be performed in a configuration employing a single electron detector.
In addition, an unmelted metal powder portion (unmelted portion) remaining in the main melting area looks slightly darker than a melted shaped object, and thus an unmelted portion can be distinguished from a melted portion. Therefore, even in a configuration employing a single electron detector, it can be determined whether a shaping surface has not been melted in the above-described shaping surface checking step.
On the other hand, an overmelted shaped object (a melted bulk) is less likely to exhibit a contrast difference because such object is a completely melted bulk although having some undulating irregularities. Therefore, in a configuration employing a single electron detector, it is difficult to determine whether a shaping surface has been overmelted in the above-described shaping surface checking step.
In
The three-dimensional PBF-AM apparatus 52 according to the second embodiment is similar in configuration to the three-dimensional PBF-AM apparatus 50 according to the first embodiment described above; the difference is a detection unit 26 that detects a backscattered electron for checking if there are irregularities on a shaping surface. Thus, the configuration of the detection unit 26 according to the second embodiment is described here, while descriptions of the configurations in common with the first embodiment are omitted.
As illustrated in
As illustrated in
The aperture member 28 faces the incident surfaces 16a and 16b of the two-segmented detectors 16A and 16B. The aperture member 28 limits the backscattered electrons to be incident on the incident surfaces 16a and 16b of the two-segmented detectors 16A and 16B. As a result, the focal depth becomes deeper, and thus irregularities on an observed surface (a shaping surface, for example) can be detected with higher accuracy.
As in the first embodiment, to check an observed surface (for example, a shaping surface of the shaped object 9), an area slightly smaller than the base plate 10 is scanned with a precisely focused electron beam to collect backscattered electron images in the second embodiment. The electron beam is generated with an emission current being low and enough to detect a backscattered electron (for example, about 1 mA).
Current amplifiers (not illustrated) are respectively connected to the two-segmented detectors 16A and 16B, and a signal A and a signal B, which are outputs from the respective current amplifiers, are transmitted to the shaping control device 60 (see
As shown in
As the detector, a pn junction type semiconductor detector used in an electron microscope, or a metal plate electrode can be used. Using a current amplifier capable of applying a voltage of about −100 V to the detector makes it possible to avoid the influence of scattered electrons of about 100 eV.
The three-dimensional PBF-AM process according to the second embodiment is the same as the three-dimensional PBF-AM process according to the first embodiment described above. In the three-dimensional PBF-AM process according to the second embodiment, the detection units 26 and 27 are used to detect a backscattered electron in the powder bed checking step and in the shaping surface checking step.
In the powder bed checking step according to the second embodiment, the electron gun drive control unit 67 (see
When it is confirmed from the acquired backscattered electron image that no irregularity is created on the powder bed (that is, the powder bed is fully covered with the powder), the CPU 64 determines that the powder bed is normal. When the CPU 64 determines that the powder bed is normal, the processing goes to the next main melting step.
On the other hand, when it is confirmed from the acquired backscattered electron image that irregularities are created on the powder bed, the CPU 64 determines that an abnormality has occurred in the powder bed. When the CPU 64 determines that an abnormality has occurred in the powder bed, the squeegeeing step is performed again, and then the powder heating step is performed again. Note that, when it is determined that an abnormality has occurred in the powder bed and the temperature of the powder bed is lower than a predetermined temperature, a process similar to the powder heating step is performed to heat the powder bed prior to returning to the squeegeeing step.
In the shaping surface checking step according to the second embodiment, the electron gun drive control unit 67 (see
The CPU 64 determines that irregularities have been created on the shaping surface if the height of a concave or convex portion exceeds a predetermined threshold. Furthermore, as in the first embodiment, in accordance with the condition of the area of irregularities, the CPU 64 determines whether the area has been overmelted or has not been melted (including insufficient melting). If the CPU 64 determines that irregularities have been created on a shaping surface during the shaping surface checking step, the re-melting step is performed. In this case, when the temperature of the shaping surface is lower than a certain temperature, a process similar to the powder heating step is performed to heat the shaping surface, and then the re-melting step is carried out.
In the re-melting step performed in the case of overmelting, the shaping surface is melted by decreasing the beam current or increasing the scanning speed. On the other hand, in the re-melting step performed in the case of unmelting, the shaping surface is melted by increasing the beam current or decreasing the scanning speed. Note that conditions for the re-melting step such as the beam current and scanning speed may be stored in the ROM 62 in advance as the shaping recipe data.
Thus, in the second embodiment, the powder bed is checked for irregularities after the powder heating step is finished, and if irregularities are found, it is determined that an abnormality has occurred in the powder bed, as in the first embodiment. Then, the squeegeeing step and the powder heating step are performed again. Accordingly, the main melting step is allowed to be performed on the powder bed in a normal state. As a result, the occurrence of a defect in the shaped object 9 can be suppressed.
In addition, the shaping surface is checked for irregularities after the main melting step is finished, and if irregularities are found on the shaping surface, the re-melting step is performed. Thus, the processing is prevented from going to the next step in the state where an abnormality has occurred on the shaping surface. As a result, the occurrence of a defect in the shaped object 9 can be suppressed. Furthermore, since the detection units 26 and 27 each include the aperture member 28 in the second embodiment, irregularities on the powder bed and on the shaping surface can be detected with high accuracy.
As illustrated in
The detection units 36 and 37 face each other in the X direction across the electron beam emission port in the electron gun 2. The distance between the centers of the detection units 36 and 37 is set to be equal to or longer than the length of at least an area to be scanned with an electron beam (substantially the same as the area of the base plate 10). Furthermore, the detection units 38 and 39 face each other in the Y direction across the electron beam emission port in the electron gun 2. The distance between the centers of the detection units 38 and 39 is set to be equal to or longer than the length of at least an area to be scanned with an electron beam (substantially the same as the area of the base plate 10).
The detection units 36, 37, 38, and 39 are in the same configuration as the configuration of the detection unit 26 (see
Needless to say, the present invention is not limited to the embodiments described above, and various other modifications and applications can be taken without departing from the gist of the appended claims.
For example, the above example embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, but the present invention is not necessarily limited to the embodiments having all the configurations described above. Furthermore, part of the configuration of an example embodiment may be replaced with the configuration of another example embodiment, or the configuration of an example embodiment may be added to the configuration of another example embodiment. Moreover, the configuration of another embodiment may be added to, replaced with, or deleted from, part of the configuration of each example embodiment.
For example, in the first and second embodiments described above, the powder bed checking step is performed after the powder heating step. However, the powder bed checking is not limited to a time point after the powder heating step but may be performed at any timing. For example, the condition of the powder bed may be checked after the squeegeeing step to detect any defect caused on the squeegee arm 13 or the blade 14.
In addition, in the shaping surface checking step carried out on the three-dimensional PBF-AM apparatus according to the present invention, whether the powder bed surface including the shaped object 9 is raised may be detected. Then, if the powder bed surface including the shaped object 9 is raised, the CPU 64 determines that the powder bed is overheated. In this case, the time period for which a surface of the shaped object 9 or a surface of the preliminary sintered body 22 (see
In the example described in the first and second embodiments above, the powder bed checking step and the shaping surface checking step are performed. However, on the three-dimensional PBF-AM apparatus according to the present invention, at least one of the powder bed checking step and the shaping surface checking step may be performed.
In addition, on the three-dimensional PBF-AM apparatus according to the present invention, it may be determined whether the backscattered electron image and the shaping data are consistent with each other regarding the dimensions of the shaped object, the shape (of a cross section) of the shaped object, and the X-direction and Y-direction coordinate positions. If the backscattered electron image and the shaping data are not consistent with each other, a distortion of the shaped object can be corrected by changing the dimensions of the melting area.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-163854 | Sep 2019 | JP | national |
