Patent Publication Number: US-2022212261-A1

Title: Am apparatus for manufacturing a fabricated object and method for testing an irradiation position of a beam in the am apparatus

Description:
TECHNICAL FIELD 
     The present application relates to an AM apparatus for manufacturing a fabricated object and a method for testing an irradiation position of a beam in the AM apparatus. The present application claims priority under the Paris Convention to Japanese Patent Application No. 2019-095153 filed on May 21, 2019. The entire disclosure of Japanese Patent Application No. 2019-095153 including the specification, the claims, the drawings, and the abstract is incorporated herein by reference in its entirety. 
     BACKGROUND ART 
     There are known techniques for directly fabricating a three-dimensional object based on three-dimensional data on a computer that expresses the three-dimensional object. Known examples thereof include the Additive Manufacturing (AM) technique. As one example, in the AM technique using metal powder, each layer of the three-dimensional object is fabricated by, toward the metal powder deposited all over a surface, irradiating a portion thereof to be fabricated with a laser beam or an electron beam serving as a heat source, and melting and solidifying or sintering the metal powder. In the AM technique, a desired three-dimensional object can be fabricated by repeating such a process. 
     CITATION LIST 
     PATENT LITERATURE 
     PTL 1: Japanese Patent Domestic Announcement No. 2016-534234 
     PTL 2: Japanese Patent Application Public Disclosure No. 2017-77671 
     SUMMARY OF INVENTION 
     TECHNICAL PROBLEM 
     In the AM technique, execution data such as an irradiation position and a beam track of the laser beam or the electron beam is generated layer by layer based on the three-dimensional CAD data that expresses the three-dimensional object targeted for the fabrication. The AM apparatus automatically carries out the additive manufacturing based on the execution data generated under computer control. Therefore, to test the execution data generated for the fabrication, the execution data is supposed to be confirmed by actually carrying out the fabrication. A simulation of the fabrication can be conducted in a virtual space on a computer, but the actual operation of the AM apparatus, the actual position irradiated with the beam, and the like cannot be tested without the AM apparatus actually put into operation. 
     If the AM apparatus malfunctions in the process of actually manufacturing the fabricated object or an error is contained in the generated execution data, this may lead to a failure to yield the fabricated object as intended or a stop of the AM apparatus in the middle of the fabrication. In this case, the fabrication is supposed to be retried after the error or the malfunction is solved, thereby wasting the material, time, and the like. Further, as the size of the manufactured fabricated object increases, the wastefulness increases when the fabrication is retried. Under these circumstances, one object of the present application is to provide a technique for testing the execution data and the operation of the AM apparatus by putting the AM apparatus into operation before actually carrying out the fabrication. 
     SOLUTION TO PROBLEM 
     According to one aspect, an AM apparatus configured to manufacture a fabricated object is provided. This AM apparatus includes a chamber defining a space used to manufacture the fabricated object, a base plate disposed in the chamber and configured to support a material of the fabricated object, a beam source configured to irradiate the material on the base plate with a beam, a computer configured to determine an irradiation position of the beam based on three-dimensional data of the fabricated object, a scanning mechanism configured to move the beam according to the determined irradiation position, a detector configured to detect an irradiation position of the beam applied into the chamber, and an evaluator configured to compare the determined irradiation position and the detected irradiation position. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  schematically illustrates an AM apparatus for manufacturing a fabricated object according to one embodiment. 
         FIG. 2  schematically illustrates the AM apparatus performing an air AM process according to one embodiment. 
         FIG. 3  is a flowchart illustrating a procedure for performing the air AM process according to one embodiment. 
         FIG. 4  is a schematic view illustrating how positional alignment is established between a beam and a detector and illustrates the detection range of the detector and the scanning range of the beam according to one embodiment. 
         FIG. 5  is a flowchart illustrating an AM process using the AM apparatus according to one embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the following description, embodiments of an AM apparatus for manufacturing a fabricated object according to the present invention will be described with reference to the attached drawings. In the attached drawings, identical or similar components may be indicated by identical or similar reference numerals, and redundant descriptions regarding the identical or similar components may be omitted in the description of each of the embodiments. Further, features described in each of the embodiments are applicable even to other embodiments in so far as they do not contradict each other. 
       FIG. 1  schematically illustrates an AM apparatus for manufacturing a fabricated object according to one embodiment. As illustrated in  FIG. 1 , an AM apparatus  100  includes a process chamber  102 . A buildup chamber  106  is attached to a bottom surface  104  of the process chamber  102 . A lift table  108  is installed in the buildup chamber  106 . The lift table  108  is movable in the vertical direction (a z direction) by a driving mechanism  110 . For example, the driving mechanism  110  may be a pneumatic or hydraulic driving mechanism or may be a driving mechanism including a motor and a ball screw. An inlet and an outlet for introducing and discharging protective gas into and out of the process chamber  102  may be provided, although they are not illustrated. 
     In one embodiment, an XY stage  112  is disposed on the lift table  108  as illustrated in  FIG. 1 . The XY stage  112  is a stage movable in two directions (an x direction and a y direction) in parallel with the plane of the lift table  108 . A base plate  114  for supporting a material of a fabricated object is disposed on the XY stage  112 . 
     A material supply mechanism  150  for supplying the material of the fabricated object is disposed above the buildup chamber  106  in the process chamber  102 . The material supply mechanism  150  includes powder  152  used as the material of the fabricated object, a storage container  154  for holding, for example, metal powder, and a movement mechanism  160  for moving the storage container  154 . The storage container  154  includes an opening  156  for discharging the material powder  152  onto the base plate  114 . The opening  156  can be, for example, a linear opening  156  longer than one side of the base plate  114 . In this case, the material powder  152  can be supplied to the entire surface of the base plate  114  by configuring the movement mechanism  160  so as to move in a range longer than the other side of the base plate  114  in a direction perpendicular to the line of the opening  156 . Further, the storage container  154  includes a valve  158  for controlling the opening/closing of the opening  156 . 
     In one embodiment, the AM apparatus  100  includes a laser light source  170 , and a scanning mechanism  174 , which guides a laser  172  emitted from the laser light source  170  toward the material powder  152  on the base plate  114 , as illustrated in  FIG. 1 . In the illustrated embodiment, the laser light source  170  and the scanning mechanism  174  are disposed in the process chamber  102 . The scanning mechanism  174  can be formed by an arbitrary optical system, and is configured to be able to irradiate an arbitrary position of a fabrication surface (a focus surface) on the base plate  114  with the laser  172 . 
     In one embodiment, an electron beam source may be used instead of the laser light source  170 . In the case where the electron beam source is used, the scanning mechanism  174  includes a magnet or the like, and is configured to be able to irradiate an arbitrary position of the fabrication surface on the base plate  114  with an electron beam. 
     In the embodiment illustrated in  FIG. 1 , the AM apparatus  100  includes a control device  200 . The control device  200  is configured to control the operations of various kinds of operation mechanisms of the AM apparatus  100 , such as the above-described driving mechanism  110 , movement mechanism  160 , laser light source  170 , scanning mechanism  174 , and valve  158  of the opening  156 . The control device  200  can be formed by a general computer or a dedicated computer. 
     When a three-dimensional object is manufactured by the AM apparatus  100  according to the embodiment illustrated in  FIG. 1 , the procedure therefor is generally as follows. First, three-dimensional data D 1  of a fabrication target is input to the control device  200 . The control device  200  generates slice data for the fabrication based on the input three-dimensional data D 1  of the fabricated object. Further, the control device  200  generates execution data including fabrication conditions and a recipe. In other words, the control device  200  functions as a computer that determines an irradiation position of the beam based on the three-dimensional data D 1  of the fabricated object. The fabrication conditions and the recipe include, for example, beam conditions, beam scanning conditions, and layering conditions. The beam conditions include voltage conditions, a laser output, and the like of the laser light source  170  in the case where the laser is used, or include a beam voltage, a beam current, and the like in the case where the electron beam is used. The beam scanning conditions include a scanning pattern, a scanning route, a scanning speed, a scanning interval, and the like. Examples of the scanning pattern include a pattern when the beam scans in one direction, a pattern when the beam scans in reciprocating directions, a pattern when the beam scans zigzag, and a pattern when the beam moves transversely while drawing a small circle. The scanning route determines, for example, in what order the beam scans. The layering conditions include, for example, a material type, an average diameter of the powder material, a particle shape, a particle size distribution, a layering thickness (a thickness in which the material powder is deposited all over the surface at the time of the fabrication), and a fabrication thickness coefficient (a ratio between the layering thickness and the thickness of the actually manufactured fabricated object). A part of the above-described fabrication conditions and recipe may be generated and changed according to the input three-dimensional data of the fabricated object or may be determined in advance independently of the input three-dimensional data of the fabricated object. 
     The powder  152  used as the material of the fabricated object, such as metal powder, is loaded into the storage container  154 . The lift table  108  of the buildup chamber  106  is moved to an upper position, by which the surface of the base plate  114  is adjusted so as to be positioned on the focus surface of the laser  172 . Next, the valve  158  of the opening  156  of the storage container  154  is opened and the storage container  154  is moved, and then the material powder  152  is evenly supplied onto the base plate  114 . The material supply mechanism  150  is controlled by the control device  200  so as to supply the material powder  152  onto the focus surface by an amount corresponding to one layer of the fabricated object (corresponding to the above-described “layering thickness”). Next, a fabricated object M 1  corresponding to one layer is created by emitting the laser  172  from the laser light source  170 , irradiating a predetermined range of the focus surface with the laser  172  by the scanning mechanism  174 , and melting and sintering the powder material at a predetermined position. At this time, the irradiation position of the laser  172  may be changed by moving the XY stage  112  disposed on the lift table  108  if necessary. 
     After the fabrication corresponding to one layer is ended, the lift table  108  of the buildup chamber  106  is lowered by a distance corresponding to one layer. The material powder  152  is supplied onto the focus surface by the material supply mechanism  150  by an amount corresponding to one layer of the fabricated object again. Then, the fabricated object M 1  corresponding to one layer is created by causing the laser  172  to scan on the focus surface by the scanning mechanism  174  and melting and sintering the material powder  152  at a predetermined position. The targeted fabricated object M 1  can be created from the powder  152  by repeating these operations. 
     As described above, if the AM apparatus malfunctions in the process of actually manufacturing the fabricated object M 1  or an error is contained in the generated execution data, this may lead to a failure to yield the fabricated object as intended or a stop of the AM apparatus in the middle of the fabrication. Therefore, the AM apparatus  100  according to one embodiment of the present disclosure includes a configuration for testing whether the AM apparatus  100  operates so as to be able to actually manufacture the fabricated object. In the present specification, the process for testing the operation of the AM apparatus will be referred to as an “air additive manufacturing process”.  FIG. 2  schematically illustrates the AM apparatus performing the air AM process according to one embodiment. The air AM process is performed without the presence of the material powder  152 . 
     The AM apparatus  100  according to one embodiment includes a detector  202  for detecting the irradiation position of the applied beam. In the embodiment illustrated in  FIG. 1 , the detector  202  is a camera  202   a . The camera  202   a  is disposed in the process chamber  102 , and is arranged so as to be able to image the entire scanning range on the focus surface of the laser  172 . Further, the camera  202   a  is assumed to be a camera that can image the focus position of the laser  172 . The camera  202   a  is connected to the control device  200 , and data imaged by the camera  202   a  can be processed by the control device  200 . 
     The AM apparatus  100  according to the present embodiment can confirm the actual operation of the AM apparatus, especially, the irradiation position and the scanning track of the laser by imaging the irradiation position of the laser  172  with use of the camera  202   a . Whether the AM apparatus operates so as to be able to appropriately manufacture the input fabricated object can be confirmed by checking the irradiation position and the scanning track of the laser  172  in all layers of the input fabricated object. This operation can be performed without the presence of the material powder  152 , thereby allowing the operation of the AM apparatus  100  to be confirmed before the fabrication is actually carried out with use of the material powder  152 . 
     In one embodiment, the AM apparatus  100  can include a sheet-shaped two-dimensional detector  202   b  (refer to  FIG. 2 ) as the detector  202  for detecting the irradiation position of the applied beam. The detector  202   b  is assumed to be able to detect the light of the laser  172 , and can be sized so as to cover the entire scanning range on the focus surface of the laser  172 . The irradiation position and the scanning track of the laser  172  can be confirmed similarly to the above-described camera  202   a  by setting up the sheet-shaped detector  202   b  on the focus surface of the laser  172 . 
     In the case where the AM apparatus is configured to use the electron beam instead of the laser  172 , the camera  202   a  is assumed to be able to image the electron beam or the sheet-shaped detector  202   b  is assumed to be able to detect the electron beam. 
     When the air AM process is performed, the intensity of the laser  172  or the electron beam is desirably set to a beam intensity lower than when the material powder  152  is sintered actually. In one embodiment, the AM apparatus  100  includes an adjustment device  171  for adjusting the intensity of the beam to be applied. This adjustment device  171  can be configured to adjust the power of electricity to be supplied to the laser light source or the electron beam source. 
       FIG. 3  is a flowchart illustrating a procedure for performing the air AM process according to one embodiment. First, the execution data for carrying out the fabrication by the AM apparatus  100  is generated based on the three-dimensional data D 1  of the fabrication target input to the control device  200 . The execution data includes, for example, the irradiation position of the beam, the fabrication conditions, and the recipe for each layer when the AM apparatus  100  fabricates the fabricated object. 
     Next, a reference position of the beam to be applied and a reference position of the detector  202 , which detects the irradiation position of the beam, are aligned with each other.  FIG. 4  is a schematic view illustrating how positional alignment is established between the beam and the detector  202 , and illustrates the detection range of the detector  202  and the scanning range of the beam. In  FIG. 4 , a rectangle indicated by an outer solid line represents a detection range  210  of the detector  202 , in particular, the imaging region of camera  202   a  or the detection range of the sheet-shaped detector  202   b . In  FIG. 4 , a broken line indicates a scanning range  212  of the beam, which is a range where the beam can scan by the scanning mechanism  174 . A long dashed short dashed line in  FIG. 4  indicates the center of the detection range of the detector  202 . 
     To positionally align the reference position of the beam and the reference position of the detector  202 , first, the detector  202  is disposed in such a manner that the entire scanning range  212  of the beam is contained in the detection range  210  of the detector  202 . Next, a reference mark  216  is placed at an arbitrary position inside the scanning range  212  of the beam. In the example illustrated in  FIG. 4 , reference marks  216  are placed at the four corners of the scanning range  212  of the beam, one for each of the four corners. The reference mark may be one reference mark. The reference mark  216  may be placed at the center of the scanning range  212  of the beam. The reference mark  216  may be a feature preset on the focus surface of the AM apparatus  100 , such as the surface of the base plate  114 . 
     Next, the position of the reference mark  216  is irradiated with the beam, and the beam with which the reference mark  216  is irradiated is detected by the detector  202 . This reveals the beam position detected by the detector  202  (the position of the reference mark  216  on the detector  202 ) and the position irradiated with the beam by the AM apparatus  100 , such as the operation position of the scanning mechanism  174  (the operation position of the scanning mechanism  174  for irradiating the position of the reference mark  216  with the beam), thereby making it possible to confirm which position an arbitrary beam position detected by the detector  202  corresponds to on the focus surface of the AM apparatus. 
     After the positional alignment can be established between the beam and the detector  202 , the beam is applied based on the execution data with use of the AM apparatus  100 . However, the intensity of the laser  172  or the electron beam to be applied is set to a beam intensity lower than when the material powder  152  is sintered actually. Further, in the air AM process, the XY stage  112  is also put into operation based on the execution data for the fabrication, but the height of the lift table  108  is not changed. The position irradiated with the beam is detected by the detector  202 . The beam position detected in the air AM process and the three-dimensional data of the fabrication target are compared and evaluated. The control device  200  can make the comparison and the evaluation between the beam position detected in the air AM process and the three-dimensional data D 1  of the fabrication target. In other words, the control device  200  functions as an evaluator for comparing and evaluating the beam position detected in the air AM process and the three-dimensional data D 1  of the fabrication target. If the detected beam position does not match the three-dimensional data of the fabrication target, it is considered that there is an error in the execution data or the operation of the AM apparatus, in particular, the operation of the scanning mechanism  174 . If the detected beam position does not match the three-dimensional data of the fabrication target and the AM apparatus  100  operates according to the recipe in the execution data, it is considered that there is an error in the execution data. Further, supplementarily, the execution data may be tested by virtually conducting a fabrication simulation without using the AM apparatus based on the execution data in a virtual space on a computer. Even when the detected beam position matches the three-dimensional data of the fabrication target in the air AM process, it is considered that there is an error in the AM apparatus and/or the execution data if the AM apparatus  100  does not operate as intended or the same position is excessively redundantly irradiated. 
       FIG. 5  is a flowchart illustrating an AM process using the AM apparatus according to one embodiment. First, the three-dimensional data of the fabrication target is input to the control device  200 . The control device  200  generates the execution data including the fabrication conditions and the recipe. Next, the AM apparatus performs the above-described air AM process. If no fault is discovered in the air AM process, the fabricated object is manufactured by performing the actual AM process. If a fault is discovered in the air AM process, the air AM process is performed again after the fault is corrected. 
     The AM apparatus according to the above-described embodiment allows the air AM process to be performed with use of the same AM apparatus before the fabrication target is actually fabricated by the AM apparatus, thereby allowing an erroneous operation of the AM apparatus and/or a defect in the data for the fabrication to be discovered before the manufacturing. Therefore, the operation of the AM apparatus, the fabrication data, and the recipe can be tested without consuming the material for the fabrication. For example, the operations of the driving mechanism  110 , which drives the lift table  108  of the AM apparatus  100 , the XY stage  112  on the base plate  114 , and the scanning mechanism  174  cannot be tested without the AM apparatus  100  actually put into operation, and therefore the virtual simulation on the computer is not sufficient to discover a malfunction in these driving mechanisms of the AM apparatus  100 . The air AM process in the embodiment according to the present disclosure can test not only the execution data but also the operation mechanisms of the AM apparatus. 
     Having described the embodiments of the present invention based on the several examples, the above-described embodiments of the present invention are intended to only facilitate the understanding of the invention, and are not intended to limit the present invention thereto. It is apparent that the present invention can be modified or improved without departing from the spirit thereof, and includes equivalents thereof. Further, each of the components described in the claims and the specification can be arbitrarily combined or omitted within a range that allows it to remain capable of achieving at least a part of the above-described objects or bringing about at least a part of the above-described advantageous effects. 
     At least the following technical ideas can be recognized from the above-described embodiments. [Configuration 1]According to a configuration 1, an AM apparatus configured to manufacture a fabricated object is provided. This AM apparatus includes a chamber defining a space used to manufacture the fabricated object, a base plate disposed in the chamber and configured to support a material of the fabricated object, a beam source configured to irradiate the material on the base plate with a beam, a computer configured to determine an irradiation position of the beam based on three-dimensional data of the fabricated object, a scanning mechanism configured to move the beam according to the determined irradiation position, a detector configured to detect an irradiation position of the beam applied into the chamber, and an evaluator configured to compare the determined irradiation position and the detected irradiation position. 
     [Configuration 2] According to a configuration 2, the AM apparatus according to the configuration  1  further includes an adjustment device configured to adjust an intensity of the beam to be applied. 
     [Configuration 3]According to a configuration 3, in the AM apparatus according to the configuration 1 or the configuration 2, the beam source is a laser source. 
     [Configuration 4] According to a configuration 4, a method for testing an irradiation position of a beam in an AM apparatus is provided. This method includes a step of preparing three-dimensional data of a fabricated object to be manufactured by the AM apparatus, a step of determining the irradiation position of the beam based on the three-dimensional data, a step of applying the beam by putting the AM apparatus into operation according to the determined irradiation position of the beam without the presence of a material of the fabricated object, a step of detecting a position of the applied beam, and a step of comparing the determined irradiation position of the beam and the detected position of the beam. 
     [Configuration 5] According to a configuration 5, in the method according to the configuration 4, the step of applying the beam is performed with a beam intensity lower than a beam intensity when the beam is applied at the time of manufacturing the fabricated object by the AM apparatus. 
     [Configuration 6] According to a configuration 6, in the method according to the configuration 4 or the configuration 5, the beam is a laser. 
     REFERENCE SIGNS LIST 
       102  process chamber 
       106  buildup chamber 
       108  lift table 
       110  driving mechanism 
       112  stage 
       114  base plate 
       150  material supply mechanism 
       152  material powder 
       154  storage container 
       160  movement mechanism 
       170  laser light source 
       171  adjustment device 
       172  laser 
       174  scanning mechanism 
       200  control device 
       202  detector 
     D 1  three-dimensional data 
     M 1  fabricated object