JP2023009555A - Powder bed evaluation device, additive manufacturing device, powder bed evaluation method and additive manufacturing method - Google Patents

Abstract

To provide a powder bed evaluation device, an additive manufacturing device, a powder bed evaluation method, and an additive manufacturing method that, when heterogeneity exists in the distribution of metal powder material in a powder bed made of the metal powder material, can detect the heterogeneity properly.SOLUTION: A powder bed evaluation device has a powder feed part 20 that feeds metal powder material P, a powder bed vessel 10 that holds a powder bed B made of the metal powder material P, a smoothing component 40 that smoothes the distribution of the metal powder material P to form the powder bed B, and a height measurement device 50 mounted on the smoothing component 40 that measures the distribution of the height on a surface of the powder bed B formed in the powder bed vessel 10 in a non-contact manner. Further, an additive manufacturing device 1 comprises an energy ray irradiation source 30 that includes the powder bed evaluation device and irradiates the powder bed B with an energy ray to make the metal powder material P on the irradiated site melted.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a powder bed evaluation apparatus, an additive manufacturing apparatus, a powder bed evaluation method, and an additive manufacturing method, and more particularly, to a powder bed capable of evaluating the state of the surface of a powder bed in which a metal powder material is spread. The present invention relates to an evaluation apparatus, a layered manufacturing apparatus, a powder bed evaluation method, and a layered manufacturing method.

As a new technique for manufacturing a three-dimensional model, additive manufacturing (AM) has developed remarkably in recent years. As one type of additive manufacturing technology, there is an additive manufacturing method that utilizes the solidification of metal powder materials by irradiation with energy beams. Examples of additive manufacturing methods using metal powder materials include Selective Laser Melting (SLM, also referred to as laser powder bed fusion method (L-PBF)) and Electron Beam Melting (EBM). etc. can be mentioned. In these methods, a metal powder material is supplied onto a base material to form a powder bed, and based on three-dimensional design data, a laser beam, an electron beam, or the like is applied to a predetermined position of the powder bed. of energy rays. Then, the metal powder material in the irradiated portion is solidified by melting and re-solidifying to form a shaped body. A three-dimensional modeled object is obtained by repeating the supply of metal powder material to the powder bed and modeling by irradiation with energy beams to sequentially form a modeled object in layers.

In the three-dimensional model obtained, a structure with uneven distribution of constituent materials, such as voids, occurs at positions corresponding to the surface of each layer when material is supplied to the powder bed and irradiated with energy rays in layers. Sometimes. It is desirable to suppress the generation of such a non-uniform structure as much as possible. Factors that cause a non-uniform structure in a three-dimensional model include non-uniform distribution of metal powder materials in the powder bed, inadequate conditions for modeling such as irradiation conditions for energy beam irradiation, and three-dimensional models to be manufactured. There are several factors, such as inappropriate design shape. Among them, as a method for evaluating the non-uniformity of the distribution of the metal powder material in the powder bed, Patent Document 1 describes a powder supply step in which the powder material is spread in layers to form a constituent layer of the powder bed, and the constituent layer While scanning the surface of the energy beam, the molding process of solidifying the powder material of the irradiated part is alternately repeated, and when manufacturing a three-dimensional model, between the powder supply process and the modeling process 2, a photographing step of photographing the surface of the constituent layer to obtain an image, and an evaluation step of obtaining evaluation data for detecting locations where the powder material distribution is uneven in the constituent layer based on the image obtained in the photographing step; A powder bed evaluation method is disclosed that performs: In Patent Document 1, as a photographing device used in the photographing process, during modeling, the purpose is to monitor defects and abnormalities in the constituent members of the device and the powder bed, and to confirm whether the modeling is progressing normally. , it is described that a camera attached to the laminate molding apparatus is also used.

JP 2018-193586 A

As described above, the three-dimensional structure obtained by the additive manufacturing method has a non-uniform structure. As a basis for taking measures to eliminate these causes, it is important to identify which cause causes the non-uniform structure in the three-dimensional structure. In that respect, as described in Patent Document 1, photographing the surface of the powder bed using a camera and analyzing the photographed image evaluates the degree of uniformity of the distribution of the metal powder material in the powder bed. However, it is effective. In particular, as mentioned in Patent Document 1, the uneven distribution of the metal powder material due to the protrusion of the three-dimensional model already formed halfway and contained in the powder bed, and the powder of the three-dimensional model Any exposure from the floor can be sensitively detected. At this time, if a surveillance camera built into the additive manufacturing apparatus is used, such evaluation of the powder bed can be performed with a simple apparatus configuration.

However, since the camera built into the additive manufacturing apparatus is originally intended for monitoring abnormalities, it is not necessarily suitable for evaluating the degree of uniformity of the metal powder material. . For example, because the spatial resolution of the camera is not very high, non-uniform distributions of metal powder materials may not be detected with sufficient spatial resolution. In addition, metal powder materials often have a black color or a dark color close to it, and even if unevenness occurs in the distribution, it is difficult to clearly recognize the unevenness as the contrast of the image captured by the camera. There is Therefore, unlike the uneven distribution of the metal powder material that is formed on a large spatial scale and with a large difference in height, such as the uneven distribution due to the influence of the three-dimensional structure that is formed halfway, the metal powder Inhomogeneous distribution formed in a short distance on the surface of the powder bed, such as inhomogeneous distribution caused by material quality, structure, and physical properties, and inhomogeneous distribution that gives only a small height difference may not be detected properly. . In this way, when trying to evaluate the distribution of the metal powder material in the powder bed using the camera built into the additive manufacturing apparatus, even if there is non-uniformity in the distribution of the metal powder material, three-dimensional The non-uniformity can be difficult to detect for sufficient information to distinguish it from other factors that contribute to the non-uniform structure of the build.

The problem to be solved by the present invention is to enable accurate detection of non-uniformity in the distribution of the metal powder material in the powder bed composed of the metal powder material. An object of the present invention is to provide an evaluation apparatus, a layered manufacturing apparatus, a powder bed evaluation method, and a layered manufacturing method.

In order to solve the above problems, the powder bed evaluation apparatus according to the present invention comprises a powder supply section that supplies a metal powder material, and a powder bed composed of the metal powder material supplied from the powder supply section on a substrate. and the metal powder material contained in the powder bed container is moved along the surface of the substrate while being in contact with the powder bed container to smooth the distribution of the metal powder material and the a smoothing member forming a powder bed; and a height measuring device attached to the smoothing member for non-contact measurement of height distribution on the surface of the powder bed formed in the powder bed container. have.

Here, the height measuring device is preferably a laser displacement meter. The height measuring device preferably has a spatial resolution of one-fifth or less of the average particle size of the metal powder material on the surface of the powder bed.

The powder bed evaluation apparatus further includes an imaging device provided above the powder bed container, and the imaging device has a lower spatial resolution than the height measurement device and a wider field of view than the height measurement device. , to photograph the surface of the powder bed. In this case, the imaging device preferably has a spatial resolution of 1 mm or less on the surface of the powder bed. Moreover, the powder bed evaluation apparatus may further include an illumination device that is provided on the side of the powder bed container and that irradiates the surface of the powder bed with light from the side.

The smoothing member is in contact with the metal powder material in the powder bed container and performs a smoothing motion that moves in one direction along the surface of the base material to smooth the distribution of the metal powder material. After that, a recursive motion is performed in a direction opposite to the smoothing motion without contacting the metal powder material, and the height measuring device moves the smoothing member during the recursive motion. Second, it is preferable to measure the height distribution on the surface of the powder bed. Alternatively, the smoothing member smoothes the distribution of the metal powder material in the powder bed vessel by a smoothing motion that moves along the surface of the substrate while in contact with the metal powder material. The height measuring device preferably measures the height distribution of the surface of the powder bed while the powder bed is being heated.

A layered manufacturing apparatus according to the present invention incorporates the above-described powder bed evaluation device, and in addition to the powder supply unit, the powder bed container, the smoothing member, and the height measurement device, is formed in the powder bed container An energy ray irradiation source is further provided for irradiating the powder bed thus formed with energy rays to melt the metal powder material at the irradiated portion.

The powder bed evaluation method according to the present invention includes a powder supply step of supplying the metal powder material from the powder supply unit to the powder bed container using the powder bed evaluation apparatus; A powder bed forming step of smoothing the distribution of the metal powder material supplied to the floor container, and a measuring step of measuring the height distribution on the surface of the powder bed by the height measuring device. is.

Here, using a powder bed evaluation apparatus equipped with the imaging device, an imaging step of imaging the surface of the powder bed with the imaging device is performed together with the measurement step, and the measurement results obtained in the measurement step. In addition to this, it is preferable to evaluate the height distribution on the surface of the powder bed using the photographed image obtained in the photographing step.

The layered manufacturing method according to the present invention includes a powder supplying step of supplying the metal powder material from the powder supply unit to the powder bed container by using the above-described layered manufacturing apparatus; A powder bed forming step of smoothing the distribution of the metal powder material supplied to the powder bed, a measuring step of measuring the height distribution on the surface of the powder bed by the height measuring device, and the energy beam irradiation source and a shaping step of irradiating the powder bed with the energy beam to melt and re-solidify the metal powder material in the irradiated portion.

Here, it is preferable to perform a photographing step of photographing the surface of the powder bed with the photographing device together with the measuring step using the layered manufacturing apparatus incorporating the powder bed evaluation device having the photographing device.

The powder bed evaluation apparatus according to the above invention includes a height measuring device for measuring the height distribution on the surface of the powder bed formed in the powder bed container. By directly measuring the height distribution on the surface of the powder bed with a height measuring device, if uneven metal powder material distribution with height differences is formed on the surface of the powder bed, the unevenness A distribution can be detected. By attaching the height measuring device to the smoothing member that smoothly spreads the metal powder material on the surface of the powder bed, it is possible to evaluate the state of the formed powder bed surface itself with high certainty. Become. Further, since the height measuring device is of a non-contact type, the measuring process for evaluating the state of the surface of the powder bed does not affect the state of the powder bed. If non-uniform distribution of the metal powder material is formed on the surface of the powder bed, the non-uniform distribution can be distinguished from other factors to form a non-uniform structure in the three-dimensional model. can be associated. In addition, the evaluation results can be used as basic information for measures to reduce non-uniform distribution in the powder bed, such as examining the material composition, shape, and particle size of the metal powder material.

Here, if the height measuring device is a laser displacement gauge, non-contact detection of non-uniform distribution of the metal powder material accompanied by height differences on the surface of the metal powder material can be performed with high spatial resolution and accuracy. can. In addition, many laser displacement meters have a lightweight and compact head part, and even if they are attached to a smoothing member such as a recoater, they do not easily affect the movement of the smoothing member and other steps in forming the powder bed. . Furthermore, the measurement results are substantially unaffected by the color of the metal powder material, and the height difference in the distribution can be detected with high accuracy even for dark-colored metal powder materials such as black.

When the height measuring device has a spatial resolution of 1/5 or less of the average particle diameter of the metal powder material on the surface of the powder bed, the distribution generated in particle units in the metal powder material constituting the powder bed Non-uniformity can also be detected. As a result, it becomes possible to consider factors that cause non-uniformity and methods for reducing the non-uniformity, while taking into account phenomena that occur in particle units, such as particle packing.

The powder bed evaluation device further has an imaging device provided above the powder bed container, and the imaging device has a lower spatial resolution than the height measurement device and a wider field of view than the height measurement device. In the case of photographing, the uneven distribution of the metal powder material that occurs on the surface of the powder bed on a fine spatial scale is detected by a height measuring device, and the metal powder material that occurs on a relatively large spatial scale is detected. A non-uniform distribution can be detected by the imager. Therefore, by combining the information obtained by the height measurement device and the imaging device, it is possible to evaluate the degree of uniformity of the distribution of the metal powder material on the surface of the powder bed at various spatial scales, and to detect uneven distribution. be able to.

In this case, if the imaging device has a spatial resolution of 1 mm or less on the surface of the powder bed, uneven distribution due to contact between the metal powder material and the smoothing member will occur. Non-uniform distributions occurring on the surface of the powder bed in the behavior of the metal powder material can be preferably detected by means of the imaging device.

In addition, if the powder bed evaluation device is provided on the side of the powder bed container and further has a lighting device that irradiates the surface of the powder bed with light from the side, uneven height distribution is formed on the surface of the powder bed. In the image obtained by the imaging device, the height distribution gives a high contrast, and it is possible to accurately evaluate the degree of uniformity of the distribution of the metal powder material and detect non-uniform distribution. easier to get to.

A smoothing member is in contact with the metal powder material in the powder bed container and performs a smoothing motion that moves in one direction along the surface of the base material to smooth the distribution of the metal powder material. Without contacting the material, a recursive movement moving in the direction opposite to the smoothing movement is performed, and the height measuring device measures the height at the surface of the powder bed during the recursive movement of the smoothing member. When measuring the distribution, even if the moving speed of the smoothing member suitable for smoothing the metal powder material and the moving speed of the height measuring device suitable for measuring the height distribution of the metal powder material are different, By performing the smoothing motion at a speed suitable for the former and performing the regression motion at a speed suitable for the latter, each process can be executed under appropriate conditions. The recursive movement is a process that is inevitably executed when the supply of the metal powder material from the powder supply unit and the smoothing of the supplied metal powder material are repeated. By performing the measurement with the device, the increase in required time is small compared with the case where such measurement is not performed.

Alternatively, while the smoothing member smoothes the distribution of the metal powder material in the powder bed vessel by a smoothing motion moving along the surface of the substrate in contact with the metal powder material, When the height measuring device measures the height distribution of the surface of the powder bed, it is possible to immediately evaluate the state of the metal powder material that has been smoothly spread by the movement of the smoothing member.

The additive manufacturing apparatus according to the above invention incorporates the above-described powder bed evaluation apparatus, and in addition to each member constituting the powder bed evaluation apparatus, an energy beam irradiation source for melting the metal powder material constituting the powder bed. I have more. Therefore, after evaluating the degree of uniformity on the surface of the powder bed with a height measuring device that constitutes the powder bed evaluation device, the surface of the powder bed can be irradiated with energy rays to form a model. . After confirming through actual measurements that a powder bed with a highly uniform surface has been formed, the three-dimensional model is formed, and uneven distribution of metal materials in the powder bed is eliminated. Additive manufacturing can proceed while suppressing the generation of non-uniform structures due to uniformity. On the other hand, if the measurement by the height measuring device detects that a non-uniform metal powder material distribution is formed on the surface of the powder bed, the additive manufacturing should be interrupted, and furthermore, the powder bed should be It is also possible to perform layered manufacturing after removing the cause of non-uniform distribution of the metal powder material.

In the powder bed evaluation method according to the above invention, in the powder bed forming step, the distribution of the metal powder material on the surface of the powder bed is smoothed by the smoothing member, then the measurement step is performed, and the height measuring device Measure the height distribution on the surface of the powder bed. Therefore, the degree of surface uniformity of the powder bed formed by the immediately preceding powder bed formation step can be evaluated by actual measurement in the measurement step. Therefore, if non-uniform distribution of the metal powder material exists on the surface of the formed powder bed, the non-uniform distribution can be accurately detected. Further, the non-uniform distribution of metal powder material detected can be distinguished from other factors and correlated with the formation of non-uniform structures in the three-dimensional object. In addition, the evaluation results can be used as basic information when considering measures for reducing non-uniform distribution in the powder bed, such as examining the material composition, shape, and particle size of the metal powder material.

Here, using a powder bed evaluation device equipped with a photographing device, the photographing step of photographing the surface of the powder bed with the photographing device is performed together with the measurement step. When the images obtained in the process are used to evaluate the smoothness of the surface of the powder bed, it is possible to obtain information about the uniformity of the distribution of the metallic powder material on the surface of the powder bed over various spatial scales. can. The cause of uneven distribution of metal powder material that forms on the surface of the powder bed is also easier to identify.

In the layered manufacturing method according to the above invention, in the powder bed forming step, after forming the powder bed, before performing the modeling step of irradiating the surface of the powder bed with the energy beam, the measuring step is performed to measure the height. The device makes measurements of the height distribution at the surface of the powder bed. By the measurement process, it is possible to evaluate the uniformity of the distribution of the metal powder material on the surface of the powder bed. A build layer can be formed by irradiation. If the measurement process detects uneven distribution of metal powder material on the surface of the powder bed, discontinue additive manufacturing or take measures to reduce the uneven distribution. can also In this way, by performing layered manufacturing while confirming that the distribution of the metal powder material in the powder bed has sufficiently high uniformity, in the three-dimensional model formed, the metal powder material It is possible to suppress the generation of a non-uniform structure due to the non-uniform distribution of . In addition, when the three-dimensional structure to be formed has a non-uniform structure, whether or not the non-uniform structure is caused by the non-uniform distribution of the metal powder material in the powder bed is determined by other factors. It can be used as basic information when verifying while distinguishing from the cause and taking measures to eliminate the cause.

Here, when performing a photographing process of photographing the surface of the powder bed with a photographing device using a layered manufacturing apparatus incorporating a powder bed evaluation device equipped with a photographing device along with a measurement step, various spatial scales Over time, additive manufacturing can be performed while actually ensuring that the distribution of the metal powder material at the surface of the powder bed has a sufficiently high uniformity. Therefore, it is possible to form a three-dimensional structure while suppressing generation of non-uniform structures that may occur on various spatial scales, and effectively improve the quality of the three-dimensional structure. In addition, it becomes easier to identify factors that give the three-dimensional modeled object a non-uniform structure.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing explaining the structure of the lamination-modeling apparatus concerning one Embodiment of this invention. It is a figure which shows the measurement result of height distribution by a laser displacement meter. (a) is an image showing the height distribution of a metal powder material with low fluidity, and a graph showing the height distribution by enlarging the position. (b) is a graph showing the relationship between surface roughness Ra and squeegee speed for two types of metal powder materials. (c) is a schematic diagram for explaining the packed state of particles for two kinds of metal powder materials. It is a figure which shows the result of the imaging|photography by the camera for powder bed imaging|photography. For each of the two types of metal powder materials, (a) is a photographed image, (b) is an image after image analysis, and (c) is a distribution of grayscale values in the linear portion in (b).

A powder bed evaluation apparatus, a layered manufacturing apparatus, a powder bed evaluation method, and a layered manufacturing method according to embodiments of the present invention will be described below in detail.

This powder bed evaluation device evaluates the uniformity of the distribution of the metal powder material on the surface of the powder bed on which the metal powder material is spread, and detects the non-uniform distribution if there is any non-uniform distribution. It is a device for The present powder bed evaluation method can be executed using the present powder bed evaluation apparatus. Further, the additive manufacturing apparatus can be configured as an apparatus that incorporates the powder bed evaluation apparatus and that can perform additive manufacturing by irradiating the powder bed with energy rays. Furthermore, this layered manufacturing method can be performed using this layered manufacturing apparatus. In the following, the explanation will focus on the additive manufacturing apparatus and the additive manufacturing method. A powder bed evaluation apparatus can be obtained by extracting equipment other than the equipment required for modeling by irradiation of energy beams. In addition, only the processes related to the formation and evaluation of the powder bed were extracted from the additive manufacturing method. can be a powder bed evaluation method.

[Laminate manufacturing equipment]
First, the configuration of a layered manufacturing apparatus according to an embodiment of the present invention will be described. FIG. 1 shows the configuration of a layered manufacturing apparatus 1 according to one embodiment of the present invention in a schematic cross-sectional view. The layered manufacturing apparatus 1 irradiates a powder bed B in which the metal powder material P is spread with energy rays such as a laser beam and an electron beam in a predetermined two-dimensional pattern to form a modeling layer (layered modeled body). It is a device that can create a three-dimensional model by repeating the steps in sequence.

The layered manufacturing apparatus 1 shown in FIG. 1 performs layered manufacturing using a metal powder material P by the LPB-F method. The layered manufacturing apparatus 1 includes a powder bed container 10, a powder supply unit 20, a laser irradiation device 30 as an energy beam irradiation source, a recoater 40 as a smoothing member, and a laser displacement meter 50 as a height measuring device. have. Furthermore, the layered manufacturing apparatus 1 has, as optional components, a powder bed imaging camera 60 as an imaging device and a side lighting 70 as an illumination device. In the layered manufacturing apparatus 1, after supplying the metal powder material P from the powder supply unit 20 to the powder bed container 10, the recoater 40 is used to form the powder bed B, and the laser irradiation device 30 is used to form the powder bed B. A three-dimensional model is manufactured by irradiating the surface with a laser beam. Furthermore, after forming the powder bed B using the recoater 40, before performing laser irradiation by the laser irradiation device 30, the laser displacement meter 50 and the powder bed imaging camera 60 measure the metal powder material P on the surface of the powder bed B. Evaluate the distribution of

The powder bed container 10 has a base material 11 and a side wall 12, and can contain a metal powder material P and hold a powder bed B inside a space surrounded by the base material 11 and the side wall 12. can. The base material 11, which is the bottom surface of the powder bed container 10, is driven by a driving device (not shown) in vertical motion M1.

The powder supply part 20 also has a bottom plate 21 and side walls 22, and can accommodate the metal powder material P in the space surrounded by the bottom plate 21 and the side walls 22. As shown in FIG. The bottom plate 21 of the powder feeder 20 is driven by a driving device (not shown) to perform vertical movement M2 independently of the substrate 11 of the powder bed container 10 . The powder bed container 10 and the powder supply section 20 are provided adjacent to each other via a common partition wall 15 forming part of the respective side walls 12, 22, and the metal stored in the powder supply section 20 is The metal powder material P can be supplied to the interior of the powder bed container 10 by moving the powder material P into the powder bed container 10 through the partition wall 15 . The powder supply unit is not limited to such a form as long as it can supply the metal powder material P to the powder bed container 10. For example, as shown in Patent Document 1, the powder bed container A container capable of discharging the metal powder material P from the bottom may be provided above 10 to serve as a powder supply section.

The recoater 40 is a member for smoothing the surface of the metal powder material P supplied to the powder bed container 10 by motion to form the powder bed B. A powder bed B can be formed by spreading the metal powder material P smoothly. The recoater 40 has a scanning part 42 that can move along the surface of the substrate 11, ie in the horizontal plane. The scanning unit 42 can continuously reciprocate through the area extending from the powder supply unit 20 to the powder bed container 10 (movement M3). A blade 41 is attached to the scanning unit 42 . The blade 41 is a plate-like member made of an elastic material such as rubber and having an edge at its tip. The blade 41 and the scanning unit 42 are provided over substantially the entire width of the powder bed container 10 (the depth direction in the drawing).

The recoater 40 moves over the partition 15 from the powder supply section 20 to the powder bed container 10 to move the metal powder material P stored in the powder supply section 20 to the powder bed container 10 by means of the blades 41 . can be done. Further, inside the powder bed container 10, the surface of the powder bed B is smoothed by sliding the blade 41 in a horizontal plane while keeping the edge of the blade 41 in contact with the surface of the powder bed B. (squeegeeing). By squeegeeing, the metal powder material P moved from the powder supply unit 20 and supplied to the powder bed container 10 can be spread as a smooth layer to form a constituent layer of the powder bed B.

The laser irradiation device 30 has a laser unit and a galvanometer scanner (both not shown), and can irradiate a predetermined position on the surface of the powder bed B with a laser beam. The laser unit generates a laser beam by laser oscillation. The galvanometer scanner consists of a combination of optical parts such as mirrors, and can irradiate a predetermined position on the surface of the powder bed B formed in the powder bed container 10 with a laser beam emitted from the laser unit. At the position irradiated with the laser beam, the metal powder material is melted and re-solidified to form the modeled object. In the galvanometer scanner, by adjusting the alignment (angle, arrangement, etc.) of each optical component, the irradiation position of the laser beam on the surface of the powder bed B can be scanned two-dimensionally, and the three-dimensional modeling to be manufactured Scanning with a laser beam is performed according to design data such as three-dimensional CAD corresponding to the design shape of the object. Note that the energy beam irradiation source provided in the layered manufacturing apparatus 1 is not necessarily limited to the laser irradiation device 30, and the powder bed B is irradiated with the energy beam to melt the metal powder material P at the irradiated portion. Any material can be used as long as it can generate an energy ray that An electron beam irradiation device can be mentioned as an energy beam irradiation source other than the laser irradiation device 30 .

As the laser displacement gauge 50, a known laser displacement gauge can be applied. Many known laser displacement meters irradiate the surface of the object to be inspected with laser light and detect the reflected light with an optical sensor, thereby measuring the height distribution (unevenness distribution) of the surface of the material in a non-contact manner. This type of laser displacement meter can be preferably used here as well. The laser displacement meter 50 is attached to the scanning section 42 that constitutes the recoater 40 , and can be moved along the surface of the substrate 11 of the powder bed container 10 by the movement of the scanning section 42 . While the scanning unit 42 moves the laser displacement gauge 50 above the surface of the powder bed B, the laser displacement gauge 50 measures the height at the position directly below, so that along the moving direction of the scanning unit 42 , the height distribution on the surface of the powder bed B can be detected. As for the timing of the measurement by the laser displacement meter 50, as will be described in detail later with respect to the layered manufacturing method, the scanning unit 42 performs a movement (smoothing movement) for squeezing the surface of the powder bed B by the blade 41. It may be performed while the squeezing is being performed, or while the squeegeeing is finished and the movement in the opposite direction (returning movement) for returning to the origin is being performed.

A general laser displacement meter has a beam spot diameter on the order of microns to several tens of microns, and measures the height of the surface of the inspection target with a spatial resolution on the order of microns to several tens of microns. can be done. Also, the resolution in height measurement is on the order of microns or less. In general, the average particle diameter of the metal powder material P used as a raw material for additive manufacturing is on the order of microns or on the order of several tens of microns. , can be preferably detected. From the viewpoint of measuring the height distribution on the surface of the powder bed B with sufficient spatial resolution, the laser displacement meter 50 measures the average particle diameter of the metal powder material P constituting the powder bed B on the surface of the powder bed B by 5 minutes. It is preferable to exhibit a spatial resolution of 1 or less of . For example, it is preferable to have a spatial resolution of 5 μm or less. In this specification, the expression "A or less" (A is a quantity having a dimension of length) with respect to spatial resolution means having a spatial resolution that can identify the object in a length region of A or less. It shall be. Conversely, with respect to the spatial resolution, the expression "A or greater" indicates that there is only a spatial resolution at which the object cannot be identified in a length region of A or greater.

In the illustrated device, the laser displacement meter 50 is assumed to be of a form that irradiates a spot-shaped beam to a position directly below and measures the height of the point directly below. Along with the movement of 42, the height distribution on the surface of the powder bed B is measured linearly. The position at which the laser displacement gauge 50 is attached to the scanning unit 42 is not particularly limited except for the edge of the blade 41 and the vicinity of the edge where the side wall 12 of the powder bed container 10 may affect, but the scanning It is preferable to attach it at or near the central portion in the width direction (the depth direction in the drawing) of the portion 42 . As the laser displacement gauge 50, a device capable of linear measurement may be used. In this case, along the width direction of the scanning unit 42, the height distribution of the area spread linearly can be collectively measured. The distribution can be measured in two dimensions. Furthermore, the height measurement device is not limited to the laser displacement meter 50, and may be of any form as long as it can measure the height distribution on the surface of the powder bed B without contact by a principle other than image capturing by a camera. can be used.

The powder bed photographing camera 60 is provided above the powder bed container 10 and is capable of photographing the surface of the powder bed B. Preferably, the powder bed photographing camera 60 is provided so as to face the surface of the powder bed B and photograph it, that is, with its photographing direction directed downward in the vertical direction. By analyzing the photographed image obtained by the powder bed photographing camera 60, the height distribution on the surface of the powder bed B can be measured based on the luminance and hue distributions. For example, when a monochrome CCD camera is used as the powder bed photographing camera 60, a portion where the metal powder material P is distributed at a high position is observed with high brightness. The powder bed photographing camera 60 has a lower spatial resolution than the laser displacement meter 50 described above and is configured as a camera capable of photographing the surface of the powder bed B over a wider field of view than the laser displacement meter 50 . Therefore, based on the obtained captured image, the height distribution formed over a larger spatial scale on the surface of the powder bed B than the height distribution detected by the laser displacement meter 50 can be preferably detected. can.

In many cases, additive manufacturing equipment is used for the purpose of monitoring defects and abnormalities in the component parts of the equipment during modeling, major defects in the powder bed, and confirming whether the modeling is progressing normally. As such, surveillance cameras (not shown) are often provided. Such a monitoring camera may also be used as the powder bed photographing camera 60, but in view of its purpose, the monitoring camera should have a spatial resolution high enough to analyze the height distribution of the surface of the powder bed B. It is often not possible to demonstrate Therefore, as the powder bed photographing camera 60, it is preferable to provide a high-performance camera that has more pixels than the surveillance camera and is capable of photographing with high spatial resolution, separately from the surveillance camera. For example, as the powder bed photographing camera 60, it is preferable to use a camera capable of obtaining a spatial resolution of 1 mm or less on the surface of the powder bed B. On the other hand, from the viewpoint of suitably detecting the height distribution formed over a spatial scale sufficiently larger than the height distribution measured by the laser displacement meter 50, the spatial resolution of the powder bed imaging camera 60 is the powder bed B It is preferable to set the thickness to 10 μm or more on the surface of . For example, a high-resolution CCD camera or CMOS camera with 2 million pixels or more and 64 million pixels or less can be suitably used as the powder bed imaging camera 60 .

The side lighting 70 is a lighting device provided on the side of the powder bed container 10 . The side lighting 70 irradiates the surface of the powder bed B with light from the side. In general, it is preferable to irradiate the surface of the powder bed B with light from an angle within 30° upward from the surface of the powder bed B. By illuminating the surface of the powder bed B from the side with the side illumination 70, the unevenness of the surface of the powder bed B gives a high brightness contrast in the photographed image obtained by the camera 60 for photographing the powder bed. The height distribution on the surface of the floor B can be clearly recognized easily. The type of lighting device used as the side lighting 70 is not particularly limited. A configuration in which they are arranged along (the depth direction of the drawing) can be preferably exemplified.

The laminate molding apparatus 1 may be provided with a lighting device (not shown) that illuminates the powder bed B from above, in addition to the side lighting 70 . The side illumination 70 is used when acquiring a photographed image for evaluating the height distribution on the surface of the powder bed B with the powder bed photographing camera 60, while the illumination device provided above the powder bed B is , powder bed photographing camera 60, or a monitoring camera separately built in the layered manufacturing apparatus 1, when confirming and monitoring the overall condition of the powder bed B and other constituent members, it can be suitably used can be done. When acquiring a photographed image for evaluating the height distribution on the surface of the powder bed B with the powder bed photographing camera 60, an image in which the contrast due to the height distribution on the surface of the powder bed B appears clearly. From the viewpoint of acquisition, it is preferable to turn off the illumination device provided above.

The layered manufacturing apparatus 1 described above is provided with a laser displacement meter 50 and a powder bed photographing camera 60 so that the height distribution of the metal powder material P on the surface of the powder bed B for performing layered manufacturing can be measured. is configured to Therefore, the formation and evaluation of the powder bed B and the layered manufacturing using the powder bed B can be completed in one apparatus. However, for the purpose of preliminarily evaluating the state of powder bed B independently of the process of actually performing layered manufacturing, it is an apparatus that only forms and evaluates powder bed B without performing layered manufacturing. , can also constitute a powder bed evaluation device. In that case, the powder bed evaluation device comprises a powder supply unit 20, a powder bed container 10, a recoater 40 as a smoothing member, and a laser displacement meter 50 as a height measuring device, and optionally, The powder bed photographing camera 60 as the photographing device and the side lighting 70 as the lighting device are provided, but the laser irradiation device 30 is not provided.

[Laminate manufacturing method]
Next, a layered manufacturing method according to an embodiment of the present invention, which is executed using the layered manufacturing apparatus 1 described above, will be described. Here, formation and evaluation of powder bed B, and manufacture of a three-dimensional structure using powder bed B are performed.

Prior to the formation of the powder bed B, the powder supply unit 20 stores the metal powder material P as the raw material of the three-dimensional structure. The component composition of the metal powder material P may be selected according to the material of the three-dimensional structure to be manufactured. In addition, the particle size of the metal powder material P may be appropriately selected in consideration of the spatial accuracy required in the three-dimensional model and the ease of forming the powder bed B, but generally in the L-PBF method The average particle size of the metal powder material P used is about 10 to 80 μm.

The production of the three-dimensional structure is carried out layer by layer. That is, in the powder bed B, the process of forming a constituent layer filled with the metal powder material P in a thin layer and irradiating the constituent layer with a laser beam to form a modeling layer, which is a layered solidified product, is repeated. By sequentially forming modeling layers in this manner, a three-dimensional model having a three-dimensional shape can be completed.

Specifically, first, in the powder supply step, the metal powder material P is supplied from the powder supply unit 20 to the powder bed container 10 . At this time, the bottom plate 21 of the powder supply unit 20 is positioned sufficiently upward so that the metal powder material P is positioned above the partition wall 15 . In this state, by pushing the metal powder material P with the blade 41 and moving the recoater 40 from the powder supply section 20 to the powder bed container 10, part of the metal powder material P in the powder supply section 20 is It can be moved over the partition 15 to the powder bed container 10 .

Next, a powder bed forming step is performed to form a constituent layer on the surface of the powder bed B. That is, in the powder bed container 10, the blade 41 is in contact with the metal powder material P, and the recoater 40 is moved along the surface of the substrate 11 (parallel to the surface of the substrate 11) (squeegeeing ), smoothing the distribution of the metal powder material P; As a result, the metal powder material P is spread over smoothly, and a new constituent layer is formed on the surface of the powder bed B. The powder feeding step and the powder bed forming step can be continuously performed by moving the recoater 40 from the powder feeding section 20 to the powder bed container 10 and further moving it in the powder bed container 10 as it is. . At this time, the movement of the recoater 40 is performed only in one direction from the powder supply section 20 toward the powder bed container 10 .

Together with or after the powder bed formation process, a measurement process is carried out to measure the height distribution of the metal powder material P on the surface of the constituent layers of the powder bed B formed in the powder bed formation process. That is, while moving the scanning unit 42 of the recoater 40, the laser displacement meter 50 is used to measure the height distribution of the metal powder material P on the surface of the powder bed B, and based on the measurement results, the powder bed B Evaluate the degree of uniformity of the metal powder material P on the surface of the .

The movement of the recoater 40 in the powder bed forming process, that is, the movement from the powder supply unit 20 toward the powder bed container 10 (movement from right to left in the figure) is defined as a smoothing movement, and the direction of the smoothing movement is If the laser displacement meter 50 is attached so that the height can be measured behind the blade 41, the measurement process is performed while performing squeegeeing by smoothing motion in the powder bed forming process, and smoothing is performed. The height of the powder bed B immediately after receiving the powder can be measured in real time by the laser displacement meter 50 . Alternatively, while the recoater 40 has finished squeegeeing in the powder bed forming process and is performing a return movement (movement from left to right in the figure) in a direction opposite to the smoothing movement for returning to the origin. Then, a measurement step may be performed to measure the height using the laser displacement meter 50 . That is, when the squeegeeing of the powder bed forming step is completed, the surface of the base material 11 of the powder bed container 10 is slightly lowered so that the blade 41 does not come into contact with the metal powder material P. The recoater 40 moves back from the end of the powder bed container 10 toward the partition wall 15, and the laser displacement meter 50 measures the height during the back motion. The speed of the return motion may be adjusted to a speed suitable for height measurement by the laser displacement meter 50 (eg, 50 to 100 mm/s).

When the layered manufacturing apparatus 1 is provided with the powder bed imaging camera 60, in the measurement step, the height distribution of the surface of the powder bed B is measured by the laser displacement meter 50, and the powder bed imaging camera 60 measures the powder. A photographing step of acquiring a photographed image of the surface of the floor B is performed, and the height distribution of the surface of the powder bed B is obtained based on the photographed image obtained in the photographing step together with the measurement results obtained in the measurement step. may be evaluated. By doing so, it is possible to obtain information about height distributions on different spatial scales from the laser displacement meter 50 and the powder bed imaging camera 60, respectively. Photographing with the powder bed photographing camera 60 may be performed at a timing when the movement of the recoater 40 does not affect the photographed image, such as after finishing the height measurement with the laser displacement meter 50 accompanied by the movement of the recoater 40. good. Moreover, when photographing, it is preferable to illuminate the surface of the powder bed B with the side lighting 70 .

After completing the measurement process and the photographing process, the modeling process is carried out next. However, as will be described in detail later, the measurement results obtained in the measurement process and the photographing process confirmed that there was an uneven height distribution on the surface of the powder bed B, which could have a non-negligible effect on additive manufacturing. In this case, the layered manufacturing method according to the present embodiment may be suspended without performing the next modeling step. Alternatively, if the uneven height distribution and the cause of the height distribution can be removed, the shaping process may be performed after removing them.

In the modeling process, the surface of the powder bed B is irradiated with a laser beam from the laser irradiation device 30 . At this time, irradiation is performed while scanning the laser beam in a predetermined two-dimensional pattern based on design data such as three-dimensional CAD data obtained by dividing the shape of the three-dimensional structure to be manufactured into thin layers. In the constituent layer of the powder bed B formed in the previous powder bed forming step, the metal powder material P in the portion irradiated with the laser beam is heated by the laser beam and melted. When the irradiation of the laser beam at that portion ends, the irradiated portion is cooled, and the once-melted metal powder material P solidifies (re-solidifies) at that location. As a result, a modeling layer corresponding to one constituent layer is formed.

By the above, the formation of one modeled layer that constitutes the three-dimensional modeled object is completed. Next, the powder feeding step and the powder bed forming step are performed again. At this time, the position of the base material 11 of the powder bed container 10 is lowered, and the position of the bottom plate 21 of the powder supply section 20 is raised. Then, by the movement of the recoater 40, the metal powder material P is supplied from the powder supply unit 20 to the powder bed container 10, and the metal powder material P is smoothed in the powder bed container 10, so that the powder bed B has a new configuration. form a layer. At this time, the new constituent layer will be laminated on the surface of the existing powder bed B containing the previously formed modeling layer. Prior to the powder supply step and the powder bed formation step, the distance by which the substrate 11 is moved downward may be set so that the height position of the surface of the powder bed B does not change before and after these steps. .

When the powder bed formation process is completed, the measurement process and the photographing process are performed again to evaluate the state of the surface of the powder bed B on which the constituent layers have been newly formed. As described above, due to the movement of the substrate 11, the height position of the surface of the powder bed B is the same as when the previous measurement process and the imaging process were performed. Measurement by the laser displacement meter 50 and photographing by the powder bed photographing camera 60 can be performed under the same conditions.

Then, the surface of the powder bed B is again irradiated with the laser beam, and the modeling process is performed. At this time, the scanning of the laser beam is performed according to the data corresponding to the layer above the layer formed in the previous modeling process, among the design data obtained by dividing the shape of the three-dimensional model into a thin layer structure. In this way, each step of powder supply step→powder bed formation step→measurement step and photographing step→modeling step→moving the substrate 11 downward→powder supply step→ . By sequentially forming layers one by one and stacking them, a three-dimensional model having a three-dimensional shape can be manufactured.

As described above, the layered manufacturing method using the layered manufacturing apparatus 1 has been described. A powder bed evaluation method that does not involve additive manufacturing can also be performed for purposes such as evaluating conditions. In those cases, among the steps described above, the steps other than the modeling step may be performed in order. That is, the powder supply process, the powder bed formation process, the measurement process, and the photographing process may be performed in this order. These steps may be repeated multiple times in sequence with the downward movement of the base material 11 interposed therebetween.

[Evaluation of state of powder bed]
Next, evaluation of the distribution state of the metal powder material P on the surface of the powder bed B based on the measurement result obtained by the laser displacement meter 50 and the photographed image obtained by the powder bed photographing camera 60 will be described in detail. .

As described above, by using the laser displacement meter 50, the height distribution of the metal powder material P on the surface of the powder bed B on a spatial scale of one or several particles of the metal powder material P can be measured. Therefore, if there is non-uniformity in the distribution in units of one or several particles of the metal powder material P, the non-uniformity can be sensitively detected.

For example, FIG. 2(a) shows the height distribution of the surface measured using a laser displacement meter for a powder bed formed using a metal powder material with relatively low fluidity. The image is a two-dimensional scan of the measurement position by the laser displacement meter, and the height distribution is mapped. The graph shows the height distribution at the displayed location in the image as a function of position. It is displayed. A distribution of light and dark is seen in the image, which can be associated with height differences formed on the surface of the powder bed due to non-uniformity in the distribution of the metal powder material. This height difference can be more clearly recognized in the graph of the height distribution, and the distance between the surface of the powder bed displayed as the horizontal axis is approximately 50 to 200 μm (sampling period: 5 μm). A protrusion appears. Moreover, the height difference of the uneven structure is approximately 50 μm or less in terms of the height position displayed on the vertical axis. The average particle diameter of the metal powder material used was 40 μm, and the period and height difference of the uneven structure observed generally corresponds to a scale of one particle or less to several particles.

That is, it is confirmed that non-uniform distribution of the metal powder material P formed on the scale of one to several particles can be detected by using the laser displacement meter 50 . The spatial distribution of the metal powder material P on such a small scale depends on the material composition of the metal powder material P, the particle shape, the particle size, and the type and size of the resulting inter-particle interaction. In many cases, it is directly related to , structure, and physical properties.

Furthermore, in FIG. 2(b), a low-flow metal powder material (same as that used in FIG. 2(a)) and a high-flow metal powder material were used for various squeegee speeds The arithmetic average roughness (Ra) obtained from the height distribution measurement by the same laser displacement meter as in FIG. According to this, Ra increases as the squeegee speed increases, regardless of which metal powder material is used. That is, a large height difference is formed on the surface of the powder bed. In addition, when comparing Ra in the case of using two kinds of metal powder materials, Ra is smaller in the case of using the highly fluid metal powder material at any squeegeeing speed. In other words, it can be seen that a powder bed with high smoothness and highly uniform distribution of the metal powder material is formed. The change in Ra with respect to the change in squeegee speed is suppressed in the case of using a highly fluid metal powder material.

From the results of FIG. 2(b), the higher the fluidity of the metal powder material, the more uniform the filling structure can be formed in the powder bed, on the scale of one or several particles, with little height difference. I understand. As schematically illustrated in FIG. 2(c), when the fluidity of the metal powder material is low, the packing density of the particles is low, and the particles are not densely packed even on the surface of the powder bed. It is considered that the distribution of particles exposed to the surface tends to form a large height difference. On the other hand, when the fluidity of the metal particles is high, the particles exhibit a high packing density, so that the particles are densely packed even on the surface of the powder bed, making it easy to expose a surface with little difference in height.

As described above, the distribution of height differences on the scale of one or several particles that can be detected by the laser displacement meter 50 often directly reflects the material, structure, and physical properties of the particles. If there is a large non-uniformity in the distribution of the metal powder material P on the scale, it can be said that the metal powder material P used is not suitable for forming a powder bed B that provides a uniform material distribution. If layered manufacturing is performed using such a metal powder material P, it is difficult to obtain a three-dimensional model with high spatial uniformity and a dense structure. Therefore, when a large non-uniformity in the distribution of the metal powder material P is detected in the measurement using the laser displacement meter 50, the metal powder material P used in the layered manufacturing should be replaced with one having high fluidity. etc. should be considered. Further, when a non-uniform structure is formed in the manufactured three-dimensional model, the cause of the non-uniform structure of the three-dimensional model can be identified by inspecting the surface of the powder bed B with the laser displacement meter 50. , in the metal powder material P itself or in other factors. If the irregularity distribution is detected on the scale of one or several particles of the metal powder material P in the inspection using the laser displacement meter 50, the cause of the formation of the non-uniform structure in the three-dimensional structure is the metal powder. There is a high probability that the problem lies in the material P itself, and as described above, replacement of the metal powder material P to be used may be considered.

In this way, by actually measuring the unevenness distribution on the surface of the powder bed B using a height measuring device that can directly measure the height distribution of the target surface, such as the laser displacement meter 50, the metal powder on the surface of the powder bed B The degree of homogeneity of the distribution of material P can be effectively assessed. Then, if a non-uniform distribution is formed, the non-uniform distribution can be accurately detected. Since the height measuring device measures the height distribution in a non-contact manner, the state of the surface of the powder bed B is not affected by the measurement. In addition, since the height measurement device is not based on image photography, the metal powder material P has a dark color such as black, and it may be difficult to recognize uneven distribution in the photographed image. However, the non-uniform distribution of the metal powder material P can be recognized regardless of the color. In particular, as the height measuring device, by using a device having a high spatial resolution such as the laser displacement meter 50, especially a device showing a high spatial resolution of 1/5 or less of the average particle size of the metal powder material P, In the metal powder material P, it is possible to sensitively detect non-uniform distribution that occurs in particle units.

By attaching a height measuring device such as a laser displacement meter 50 to the recoater 40 for smoothing the powder bed B, the surface of the powder bed B formed by smoothing by the recoater 40 is measured. , height distribution can be reliably measured. In addition, by utilizing the motion of the recoater 40, the measurement can be performed over a wide area of the surface of the powder bed B, and the measurement is performed directly above the surface of the powder bed B. Therefore, the height distribution of the surface of the powder bed B is highly reliable. It is possible to obtain information with high quality. In many cases, the head portion of the laser displacement meter is lightweight and small, and even if it is attached to the recoater 40, it does not significantly affect the movement of the recoater 40.

As described above, the measurement of the height distribution by the laser displacement meter 50 can be performed while the recoater 40 is performing a smoothing motion for smoothing the surface of the powder bed B in one direction. . Then, the state of the surface of the smoothed powder bed B can be immediately evaluated. However, the measurement of the height distribution by the laser displacement meter 50 is preferably performed while the recoater 40 finishes the smoothing movement and performs the recursive movement in the opposite direction. Then, while the smoothing motion is performed at a motion speed suitable for smoothing the surface of the powder bed B by the blade 41, the return motion can be performed at a motion speed suitable for measuring the height distribution by the laser displacement meter 50. can. The motion speed suitable for the step of smoothing the metal powder material P and the motion speed suitable for the step of measuring the height distribution generally do not match in many cases. By dividing the time of exercise and the time of return exercise, both steps can be performed at speeds suitable for each. The recursive motion is inevitably required in lamination molding when the process of repeatedly supplying the metal powder material P to form the constituent layers of the powder bed B and performing lamination molding by irradiating a laser beam is repeated multiple times. By measuring the height distribution of the surface of the powder bed B during the return movement, the time can be used effectively.

As described above, the height measurement means such as the laser displacement meter 50 can be used to sensitively detect the non-uniform distribution of the metal powder material P on a microscale. A combination of devices can jointly detect non-uniform distributions occurring at larger spatial scales. Fig. 3(a) shows a powder bed formed by using a metal powder material with high fluidity (upper) and a metal powder material with low fluidity (lower), while illuminating the powder with side lighting. The photographed image photographed by the floor photographing camera is shown (image size: 100 mm×120 mm). According to this, it can be seen that when a metal powder material with low fluidity is used, a rough striped non-uniform distribution is formed. The brighter the observed location, the higher the distribution of the metal powder material. FIG. 3(b) is a photographed image obtained by performing analysis processing on the photographed image of FIG. 3(a). Here, as the analysis processing, the photographed image is averaged by a moving average filter of n×n pixels to create a processed image 1, and after subtracting the processed image 1 from the original photographed image, It is preferable to obtain the processed image 2 by performing the integration process with a predetermined value. The image in FIG. 3(b) is also obtained by performing such processing on the photographed image in FIG. 3(a). As the kernel used for the moving average filter, it is desirable to use pixels having a spatial resolution of at least 50 times the spatial resolution of the powder bed imaging camera 60 . Further, FIG. 3(c) shows the distribution of grayscale values in the straight line portion in the analytical image of FIG. 3(b). In the graph of FIG. 3(c), the difference in grayscale value indicates the height difference on the surface of the powder bed B. In FIG. The difference in gray scale value is not necessarily proportional to the difference in height, but the tendency of the magnitude of the value corresponds to each other.

According to FIG. 3(c), when a metal powder material with low fluidity is used, the difference in grayscale value depending on the position is larger than when a metal powder material with high fluidity is used. In other words, the height difference is large, and the non-uniformity of the distribution of the metal powder material is large. When using a metal powder material with low fluidity, the height difference is approximately several millimeters to several tens of millimeters in terms of the distance on the surface of the powder bed indicated on the horizontal axis (sampling period: 50 μm). Concave portions and convex portions appear. The scale of the horizontal axis on which this distribution of height differences occurs is considerably larger than the scale of the height distribution (50 to 200 μm) obtained by measurement with a laser displacement meter in FIG. The macro non-uniform distribution of the metal powder material formed on this scale is not a phenomenon that occurs in individual particles but directly due to the properties of the metal powder material, such as the material, structure, and physical properties of the metal powder material. It relates to the properties of the metal powder material as a powder that is an aggregate. For example, the striped non-uniform distribution observed in FIG. It is thought that the phenomenon etc. are related.

The non-uniform distribution of the metal powder material P over a relatively large scale, which is grasped from the captured image of the powder bed imaging camera 60, is also different from the non-uniform distribution occurring on a small scale in particle units detected by the measurement by the laser displacement meter 50. Similarly, in a three-dimensional model obtained by lamination manufacturing, it can be a factor that gives a non-uniform structure. Therefore, in the photographed image obtained by the powder bed photographing camera 60, when a large non-uniformity in the distribution of the metal powder material P is detected, the metal powder material P to be used is replaced, and the blade 41 of the recoater 40 is replaced. , changing the conditions for forming the powder bed B, such as the squeegee speed and the thickness of the constituent layer to be formed, may be considered. At this time, based on the obtained image data, if the degree of uniformity of the distribution of the metal powder material P is quantified by the amplitude, frequency, average value, etc. of the luminance distribution, various factors and the metal powder material P It may be possible to quantify the relationship between the degree of homogeneity of the distribution of . It should be noted that the non-uniform distribution of millimeter-order or larger scales detected on the surface of the powder bed B during layered manufacturing may be affected by the exposure of the lower-layer modeled body that has already been formed, or the effect of the lower-layered modeled body. As described in Patent Document 1, there are some things that can be detected using a monitoring camera built into the layered manufacturing apparatus 1, such as uneven distribution of the metal powder material P due to The resulting non-uniform distribution of the metal powder material P can also be detected from the captured image of the powder bed imaging camera 60 . If nonuniform distribution of the metal powder material P due to the shape of the three-dimensional model is detected, it is sufficient to consider changing the design shape of the three-dimensional model, changing the conditions for powder bed formation, etc. .

In the additive manufacturing apparatus 1 and the powder bed evaluation apparatus, a height measuring device capable of detecting a microscale unevenness distribution, such as a laser displacement meter 50, and a wide area, although inferior in spatial resolution, are used. By providing both the powder bed photographing camera 60 capable of detecting the uneven distribution of the macroscale, the unevenness of the height formed by the metal powder material P over various spatial scales on the surface of the powder bed B can be detected. A distribution can be detected and the degree of homogeneity of the distribution can be assessed. As described above, the non-uniform distribution caused by the particle properties of the metal powder material P and the non-uniform distribution caused by the powder properties are different in spatial scale, and the former non-uniform distribution formed on a micro scale. The uniform distribution can be sensitively detected by the laser displacement meter 50 , while the latter non-uniform distribution formed on a macro scale can be sensitively detected by the powder bed imaging camera 60 .

As the powder bed photographing camera 60, if a camera that exhibits a spatial resolution of 1 mm or less on the surface of the powder bed B is used, the interference with the blade 41 and the like caused by the characteristics of the metal powder material P as a powder can be eliminated. A uniform distribution can be sensitively detected. In addition, if the number of pixels of the powder bed imaging camera 60 is about 5 million pixels or more and 20 million pixels or less, sufficient spatial resolution and a wide field of view to detect the uneven distribution of them are sufficiently compatible. It's easy to do. In addition, when obtaining a photographed image by the powder bed photographing camera 60, the side illumination 70 is used to illuminate the surface of the powder bed B from the side, so that the portion where the metal powder material P is distributed at a high position However, it is more brightly illuminated than the locations distributed at lower positions, and tends to give a significantly higher luminance in the photographed image. Therefore, in the photographed image, the height difference in the distribution of the metal powder material P gives a high contrast.

The embodiments of the present invention have been described above. The present invention is not particularly limited to these embodiments, and various modifications are possible.

1 Layered Modeling Apparatus 10 Powder Bed Container 11 Base Material 15 Partition Wall 20 Powder Supply Portion 21 Bottom Plate 30 Laser Irradiation Device (Energy Ray Irradiation Source)
40 recoater (smoothing member)
41 blade 42 scanning unit 50 laser displacement meter (height measuring device)
60 powder bed imaging camera (imaging device)
70 (Side) Lighting device B Powder bed P Metal powder material

Claims (13)

a powder supply unit that supplies a metal powder material;
a powder bed container for holding, on a substrate, a powder bed composed of the metal powder material supplied from the powder supply unit;
A smoothing member configured to move along the surface of the substrate while in contact with the powder metal material contained in the powder bed container to smooth the distribution of the powder metal material to form the powder bed. When,
a height measurement device attached to the smoothing member for non-contact measurement of height distribution on the surface of the powder bed formed in the powder bed container. The powder evaluation device according to claim 1, wherein the height measurement device is a laser displacement meter. 3. The powder bed evaluation apparatus according to claim 1, wherein said height measuring device has a spatial resolution of 1/5 or less of the average particle size of said metal powder material on the surface of said powder bed. The powder bed evaluation device further has an imaging device provided above the powder bed container,
3. The powder bed evaluation apparatus according to claim 1, wherein the photographing device photographs the surface of the powder bed with a spatial resolution lower than that of the height measuring device and over a wider field of view than the height measuring device. . 5. The powder bed evaluation apparatus according to claim 4, wherein said imaging device has a spatial resolution of 1 mm or less on the surface of said powder bed. 6. The powder bed evaluation apparatus according to claim 4 or 5, further comprising an illumination device provided on the side of the powder bed container for irradiating the surface of the powder bed with light from the side. The smoothing member is in contact with the metal powder material in the powder bed container and performs a smoothing motion that moves in one direction along the surface of the base material to smooth the distribution of the metal powder material. After that, perform a return motion in a direction opposite to the smoothing motion without contacting the metal powder material,
7. The height measuring device according to any one of claims 1 to 6, wherein the height measuring device measures the height distribution on the surface of the powder bed while the smoothing member is performing the recursive motion. powder bed evaluation equipment. The smoothing member smoothes the distribution of the metal powder material in the powder bed vessel by a smoothing movement that moves along the surface of the substrate while in contact with the metal powder material. 7. A powder bed evaluation apparatus according to any one of claims 1 to 6, wherein the height measuring device measures the height distribution of the surface of the powder bed in between. Built-in the powder bed evaluation device according to any one of claims 1 to 8,
In addition to the powder supply unit, the powder bed container, the smoothing member, and the height measuring device,
A layered manufacturing apparatus further comprising an energy ray irradiation source for irradiating the powder bed formed in the powder bed container with an energy ray to melt the metal powder material in the irradiated portion. Using the powder bed evaluation device according to any one of claims 1 to 8,
a powder supply step of supplying the metal powder material from the powder supply unit to the powder bed container;
a powder bed forming step of smoothing the distribution of the metal powder material supplied to the powder bed vessel by the smoothing member;
and a measuring step of measuring the height distribution on the surface of the powder bed with the height measuring device. Using the powder bed evaluation device according to any one of claims 4 to 6 comprising the imaging device,
Performing a photographing step of photographing the surface of the powder bed with the photographing device together with the measuring step,
11. The powder bed evaluation method according to claim 10, wherein the height distribution on the surface of the powder bed is evaluated using the photographed image obtained in the photographing step together with the measurement result obtained in the measurement step. . Using the layered modeling apparatus according to claim 9,
a powder supply step of supplying the metal powder material from the powder supply unit to the powder bed container;
a powder bed forming step of smoothing the distribution of the metal powder material supplied to the powder bed vessel by the smoothing member;
a measuring step of measuring the height distribution on the surface of the powder bed with the height measuring device;
and a modeling step of irradiating the powder bed with the energy ray from the energy ray irradiation source to melt and re-solidify the metal powder material in the irradiated portion a plurality of times. Using the layered manufacturing apparatus incorporating the powder bed evaluation apparatus according to any one of claims 4 to 6, which includes the imaging device,
13. The layered manufacturing method according to claim 12, wherein a photographing step of photographing the surface of said powder bed with said photographing device is carried out together with said measuring step.

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