Additive manufacturing apparatus and additive manufacturing method

Abstract

The present invention provides an additive manufacturing apparatus and method that can prevent molding defects caused by fumes and ensure sufficient quality of the molded products. [Solution] The additive manufacturing apparatus 1A comprises a chamber 2 that forms a sealed space S, a stage 41 provided in the chamber 2 on which powder P, which is the raw material for the molded object M made by additive manufacturing, is placed, at least one laser 6 that irradiates the powder P with laser light, and a control unit that controls the laser 6. The control unit includes a determination unit that determines whether the minimum screen length of the molded object M is greater than or equal to a predetermined length determined based on the amount of fumes F generated during the molding of the molded object M.

Description

Technical Field

[0001] The present disclosure relates to an additive manufacturing apparatus and an additive manufacturing method.

Background Art

[0002] Additive manufacturing techniques have been conventionally known. Additive Manufacturing (AM) is a process of creating an object from a three-dimensional numerical representation by depositing material, which is in contrast to subtractive manufacturing. Additive manufacturing, also called "3D printing" or layered manufacturing, is in many cases realized by laminating a plurality of layers.

[0003] In powder bed type additive manufacturing technology, a laid powder is irradiated with a laser beam or the like to be melted and solidified, and this process is repeated for a plurality of layers to form a three-dimensional shaped object. Here, fumes (metal vapor) generated during shaping directly interfere with the laser, so that the laser beam is absorbed by the fumes or scattered by the fumes, which may cause defects such as poor fusion. Therefore, it was necessary to take countermeasures against fumes generated during shaping. As a fume countermeasure technology in a conventional additive manufacturing apparatus, for example, the following Patent Document 1 is known.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0005] One possible method to prevent fume interference with the laser is to circulate gas through the build chamber to exhaust the fumes. However, because the gas forms a circulating vortex, the fumes remain in the chamber, making it impossible to completely suppress fume interference with the laser, which poses a risk of degrading build quality. Furthermore, Patent Document 1 has the problem that it is difficult to control the process because it is not possible to measure the amount of fumes, making it impossible to confirm whether the fumes have been reliably removed.

[0006] Thus, the technologies reported to date have not yet been able to effectively prevent fume interference with lasers, and have therefore faced the challenge of not being able to adequately ensure the quality of fabricated products.

[0007] This disclosure is made in view of these circumstances and aims to provide an additive manufacturing apparatus and additive manufacturing method that can prevent molding defects caused by fumes and ensure sufficient quality of the molded product. [Means for solving the problem]

[0008] To solve the above problems, the additive manufacturing apparatus of the present disclosure comprises a chamber that forms a sealed space, a stage provided in the chamber on which powder, which is the raw material for an object manufactured by additive manufacturing, is placed, at least one laser that irradiates the powder with laser light, and a control unit that controls the laser, wherein the control unit includes a determination unit that determines whether the minimum screen length of the object is greater than or equal to a predetermined length determined based on the amount of fume generated during the manufacturing of the object.

[0009] The additive manufacturing method of this disclosure is an additive manufacturing apparatus comprising: a chamber forming a sealed space; a stage provided in the chamber on which powder, which is the raw material for an additively manufactured object, is placed; and at least one laser for irradiating the powder with laser light, wherein the additive manufacturing method comprises: a determination step of determining whether the minimum screen length of the manufactured object is greater than or equal to a predetermined length determined based on the amount of fumes generated during the manufacturing of the manufactured object; and a manufacturing step of irradiating the powder with laser light using the additive manufacturing apparatus to melt and bond the powder and manufacture an object. [Effects of the Invention]

[0010] The additive manufacturing apparatus and method of this disclosure make it possible to make a preliminary determination of whether or not the fabricated object will be affected by fumes during fabrication, based on the minimum canvas length of the fabricated object. Therefore, fabrication defects due to fumes can be prevented. This ensures sufficient quality of the fabricated product. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of an additive manufacturing apparatus according to the first embodiment of the present disclosure. [Figure 2] This figure shows the configuration of the control unit according to the first embodiment of this disclosure. [Figure 3A] This is an example showing the span length of a certain object. [Figure 3B] This is an example showing the span length of another object. [Figure 3C] This figure shows the results of additive manufacturing performed on the fabricated objects in Figure 3A and Figure 3B by changing the laser conditions. [Figure 4A] This is an illustrative diagram showing the flow of fumes when using a single laser. [Figure 4B] This is an illustrative diagram showing the flow of fumes when using two lasers. [Figure 5] This is a flowchart showing an additive manufacturing method according to the first embodiment of this disclosure. [Figure 6]This is a schematic configuration diagram of an additive manufacturing apparatus according to the second embodiment of the present disclosure. [Figure 7] This is a schematic configuration diagram of an additive manufacturing apparatus according to a modification of the second embodiment of the present disclosure. [Figure 8] This is a schematic configuration diagram of an additive manufacturing apparatus according to the third embodiment of the present disclosure. [Mode for Carrying Out the Invention]

[0012] Hereinafter, an embodiment of the additive manufacturing apparatus and the additive manufacturing method according to the present disclosure will be described with reference to the drawings.

[0013] [First Embodiment] Hereinafter, the first embodiment of the present disclosure will be described with reference to FIGS. 1 to 5. FIG. 1 is a schematic configuration diagram showing the additive manufacturing apparatus 1A of the present embodiment. The additive manufacturing apparatus 1A of the present embodiment is, for example, a powder bed fusion type additive manufacturing apparatus that manufactures a shaped object M by melting and bonding powder P of an additive manufacturing material using laser light.

[0014] The additive manufacturing apparatus 1A of the present embodiment includes a chamber 2, a material supply unit 3, an additive manufacturing unit 4, a recoater 5, a laser 6, and a fume suction mechanism 7A. The material supply unit 3 has a stage 31 for supplying the powder P of the additive manufacturing material, and the additive manufacturing unit 4 has a stage 41 for additive manufacturing.

[0015] The chamber 2 forms a closed space S, and accommodates each component of the additive manufacturing apparatus 1A inside the closed space S, except for a part of the fume suction mechanism 7A and the laser 6. The chamber 2 has, for example, a transmission window 21 fitted with a protective glass. The transmission window 21 transmits the laser light emitted from the laser 6 arranged outside the chamber 2, and allows the laser light to reach the powder P of the additive manufacturing material placed on the stage 41 of the additive manufacturing unit 4 inside the chamber 2.

[0016] A gas inlet 22 is formed in the upper part of one side of the chamber 2. A gas outlet 23 is formed in the lower part of the other side of the chamber 2 so as to face the gas inlet 22. In this way, the structure is configured such that gas flows through the sealed space S from the gas inlet 22 to the gas outlet 23, and fumes F staying in the sealed space S are discharged to the outside. Most of the fumes F are discharged from the gas outlet 23 along with the gas flow, but some of the fumes F remain in the chamber 2. These remaining fumes F are sucked by a fume suction mechanism 7A described later.

[0017] The material supply unit 3 is a concave portion surrounded by a side wall and a bottom wall. The bottom wall of the material supply unit 3 is constituted by a stage 31 for material supply. The material supply unit 3 is open at the top and has an opening at the upper end of the side wall, and the powder P of the additive manufacturing material is placed on the stage 31 for material supply. The stage 31 for material supply is provided so as to be able to move up and down at a predetermined pitch by, for example, an appropriate lifting mechanism.

[0018] The additive manufacturing material used for additive manufacturing of the modeled object M is not particularly limited, and for example, powders of metal materials such as copper, titanium alloys, nickel alloys, aluminum alloys, cobalt-chromium alloys, and stainless steel, powders of resin materials such as polyamide, ceramic powders, and the like can be used.

[0019] Similar to the material supply unit 3 described above, the additive manufacturing unit 4 is a concave portion surrounded by a side wall and a bottom wall. The bottom wall of the additive manufacturing unit 4 is constituted by a stage 41 for additive manufacturing. Similar to the material supply unit 3, the additive manufacturing unit 4 is open at the top and has an opening at the upper end of the side wall, and on the stage 41 for additive manufacturing, the powder P of the additive manufacturing material supplied from the material supply unit 3 and the modeled object M manufactured by additive manufacturing are placed. The opening of the additive manufacturing unit 4 and the opening of the material supply unit 3 are approximately equal in vertical height and are arranged substantially in the horizontal direction. The stage 41 for additive manufacturing is provided so as to be able to move up and down at a predetermined pitch by, for example, an appropriate lifting mechanism, similarly to the stage 31 for material supply described above.

[0020] The recoater 5 is provided to move approximately horizontally along the openings of the material supply unit 3 and the additive manufacturing unit 4 by an appropriate moving mechanism. The recoater 5 is provided to be able to reciprocate in its direction of movement. When supplying the additive manufacturing material powder P from the material supply unit 3 to the additive manufacturing unit 4, the recoater 5 moves from a position in front of the opening of the material supply unit 3, across the opening of the material supply unit 3, to a position facing the opening of the additive manufacturing unit 4.

[0021] Laser 6 is used to irradiate the powder P with laser light. As laser 6, a known laser used in additive manufacturing can be used. In this embodiment, a configuration in which only one laser 6 is used is described, but it is also possible to use two or more lasers.

[0022] The fume suction mechanism 7A comprises a suction port 71, a suction tube 72, a pump 73, and a measuring instrument 74. The fume suction mechanism 7A removes fumes F that are trapped in the sealed space S when the recoater 5 reciprocates within the chamber 2 during powder laying after each layer is formed.

[0023] The suction port 71 is located at the top of the recoater 5 and opens upward. A suction tube 72 is connected to the suction port 71, and the suction tube 72 is provided to penetrate the side wall of the chamber 2 from the inside to the outside. An extension mechanism 75 is provided on the portion of the suction tube 72 that is on the inside side of the chamber 2. The extension mechanism 75 is bellows-shaped and can extend and retract horizontally. In this way, the extension mechanism 75 is configured to extend and retract in accordance with the horizontal movement of the recoater 5 and the suction tube 72 provided on the recoater 5.

[0024] The pump 73 is located outside the chamber 2 and is connected to the suction port 71 via a suction tube 72. The pump 73 applies suction force to the suction port 71. Any known pump can be used as the pump 73, as long as it is capable of applying sufficient suction force to draw out the fume F from the suction port 71.

[0025] The measuring instrument 74 is located outside the chamber 2 and is connected to the pump 73 via a suction tube 72. The fume F sucked in from the suction port 71 is supplied to the measuring instrument 74 through the inside of the suction tube 72. The measuring instrument 74 measures the amount of fume F supplied from the suction port 71. By measuring the amount of fume F, the amount of fume F remaining in the chamber 2 is monitored. The amount of fume F can be measured by a known method.

[0026] The additive manufacturing apparatus 1A of this embodiment includes a control unit 50. Figure 2 is a diagram showing the configuration of the control unit 50 according to this embodiment. As shown in Figure 2, the control unit 50 includes a determination unit 51 and a measurement unit 52. The control unit 50 is composed of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions are stored in the storage medium in the form of a program, for example. The CPU reads this program into the RAM and performs information processing and calculations to realize the various functions. The program may be pre-installed in the ROM or other storage medium, provided in a state where it is stored in a computer-readable storage medium, or distributed via wired or wireless communication. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memory, etc.

[0027] The determination unit 51 determines whether the minimum span length of the printed object M is greater than or equal to a predetermined length determined based on the amount of fume F generated during the printing of the printed object M. More specifically, the minimum span length of the printed object M refers to the span length of the thin-walled portion of the printed object M. Since this span length changes depending on the scan angle, it is not necessarily the span length at the thinnest portion. The predetermined length is determined based on the amount of fume F generated during the printing of the printed object M. The amount of fume F generated during the printing of the printed object M is measured in advance by performing a printing test of the printed object M. If the determination unit 51 determines that the condition is met, it is judged that stable printing quality can be ensured. On the other hand, if the determination unit 51 determines that the condition is not met, fume countermeasures will be necessary.

[0028] The reason for performing the determination by the determination unit 51 as described above will be explained. Figure 3A is an example showing the span length of a certain molded object. Figure 3B is an example showing the span length of another molded object. In the molded object in Figure 3A, there are parts with span lengths of 0.5 mm and parts with span lengths of 1.4 mm. In the molded object in Figure 3B, there is a part with a span length of 1.8 mm. Both molded objects were manufactured by changing the laser conditions, and the molding quality of these parts was confirmed.

[0029] Figure 3C shows the results of additive manufacturing performed on the fabricated objects in Figure 3A and Figure 3B by changing the laser conditions. Under the conditions of a set power of 200W and a set beam diameter of 50μm, defects were formed in the 0.5mm area, but not in the 1.4mm and 1.8mm areas. Next, under the conditions of a set power of 195W and a set beam diameter of 85μm, although the amount of fume increased, defects were formed only in the 0.5mm area, similar to the conditions of a set power of 200W and a set beam diameter of 50μm. On the other hand, under the conditions of a set power of 189W and a set beam diameter of 110μm, the amount of fume increased further, and defects were formed not only in the 0.5mm area but also in the 1.4mm area. No defects were formed in the 1.8mm area.

[0030] Thus, the amount of fumes changes each time the laser conditions are changed. In particular, when the laser campus length is short, it can be seen that an increase in the amount of fumes makes it easier for defects to form due to the influence of fumes. On the other hand, if a certain amount of laser campus length is maintained, the penetration depth gradually stabilizes, so even if affected by fumes, defect formation becomes less likely.

[0031] Thus, when a large amount of fumes are generated, the quality of the laser light deteriorates in proportion to the amount of fumes. Specifically, the output of the laser light decreases and the beam diameter increases. This reduces the heat input energy density, making the penetration depth unstable and increasing the probability of defect occurrence. In particular, since the laser light does not reach the set output immediately after oscillation but gradually approaches the set value, the penetration depth tends to be unstable immediately after oscillation. Therefore, even under optimal conditions that result in fewer defects (usually an output of several hundred watts and a scanning speed of several hundred to several thousand mm / s) when the canvas length is short, the penetration depth becomes unstable. In this case, the instability increases further when affected by fumes. Therefore, by performing a determination by the determination unit 51, it is possible to make a preliminary determination of whether or not the fabricated object M will be affected by fumes during fabrication, based on the minimum canvas length of the fabricated object M.

[0032] The measurement unit 52 measures the amount of fume F in the chamber 2. The measurement unit 52 receives measurement data from the measuring instrument 74 and measures the amount of fume F. When there is one laser 6, the measurement unit 52 measures the amount of fume F accumulating in the chamber 2. On the other hand, when there are two or more lasers 6, the measurement unit 52 measures the amount of fume F near the area in the chamber 2 that is irradiated by the laser light. In other words, the measurement unit 52 measures the amount of fume F at different locations in the chamber 2 according to the number of lasers 6.

[0033] The reason why the measurement unit 52 measures the amount of fume F at different locations within the chamber 2 according to the number of lasers 6 will be explained. First, the flow of fume F when one laser 6 is used will be explained. Figure 4A is an illustrative diagram showing the flow of fume F when one laser 6 is used. As shown in Figure 4A, when laser light L is irradiated from the laser 6 to a part of the powder P, the powder P at the irradiated area is melted and joined. At this time, fume F is generated from the irradiated area. As the gas flow through the chamber flows in the direction of the white arrow, the generated fume F flows in the direction of the black arrow. Therefore, when one laser 6 is used, it is not necessary to consider the effect of fume F near the area irradiated by the laser light on the laser 6, and it is only necessary to consider the effect of fume F accumulating in the chamber on the laser 6.

[0034] Next, we will explain the flow of fumes F when two or more lasers 6 are used. Figure 4B is an illustrative diagram showing the flow of fumes F when two lasers 6 are used. As shown in Figure 4B, two lasers 6 are provided on the upstream and downstream sides of the gas flow. When laser light L is irradiated from the two lasers 6 onto a part of the powder P, the powder in the irradiated area is melted and joined. At this time, the fumes F generated from the irradiated area on the upstream side of the gas flow gradually spread and flow downstream along with the gas flow. Therefore, the fumes F that spread and flow in this way affect the laser light L of the laser 6 located on the downstream side of the gas flow. In addition, the fumes F generated near the irradiated area have a higher concentration than the fumes F that remain in the chamber, so their effect on the lasers 6 is also greater. Therefore, when two lasers 6 are used, the effect of the fumes F near the irradiated area on the lasers 6 is greater than the effect of the fumes F that remain in the chamber on the lasers 6.

[0035] Furthermore, if the determination unit 51 determines that the result is negative, the measurement unit 52 measures the amount of fume F. In other words, if the determination unit 51 determines that the result is positive, it is determined that stable molding quality can be ensured, and therefore there is no need to measure the amount of fume F.

[0036] Next, an example of an additive manufacturing method using the control unit 50 described above will be explained with reference to Figure 5. Figure 5 is a flowchart of the additive manufacturing method of this embodiment.

[0037] First, it is determined whether or not there is any influence from fumes that directly interfere with the laser. In step S101, before fabricating the object M, the model of the object M is checked and the minimum value of the laser 6's span length (minimum span length) is confirmed.

[0038] In step S102, it is determined whether the minimum canvas length of the printed object M is greater than or equal to a specified value. The specified value is a predetermined length determined based on the amount of fume F generated during the printing of the printed object M.

[0039] If a suitable result is obtained in step S102, it is determined that the object can be fabricated (step S103). Therefore, the fabrication of the object M proceeds.

[0040] If the result in step S102 is negative, proceed to step S104. In step S104, determine whether one laser is to be used or not. If one laser is to be used, proceed to step S105. If two or more lasers are to be used, proceed to step S107.

[0041] In step S105, it is determined whether the amount of fume (low-concentration fume) remaining in the chamber 2 is below the criteria. For this determination, the amount of fume F remaining in the chamber 2 is measured. In this embodiment, the fume F is sucked from the suction port 71 by the fume suction mechanism 7A and measured by the measuring instrument 74. If the measured value is below the criteria, the process proceeds to step S103. On the other hand, if the measured value exceeds the criteria, the process proceeds to step S106. The measurement of the amount of fume F may be performed before or during the molding process.

[0042] In step S106, measures are taken to address the fumes F accumulating in the chamber 2. For example, the fumes F accumulating in the chamber 2 are removed. In this embodiment, the fumes F accumulating in the chamber 2 are removed by suction from the suction port 71 using the fume suction mechanism 7A. After the measures are taken, the process returns to step S105, and step S106 is repeated until the measured value falls below the standard amount.

[0043] If two or more lasers are used, the process proceeds from step S104 to step S107. In step S107, it is determined whether the amount of fume F (high-concentration fume) near the area irradiated by the laser light in the chamber 2 is below the criteria. For this determination, the amount of fume F near the area irradiated by the laser light in the chamber 2 is measured. For example, in the fume suction mechanism 7C of the modified second embodiment described later, fume F is sucked from the suction port 71 and measured with the measuring instrument 74. If the measured value is below the criteria, the process proceeds to step S108. On the other hand, if the measured value exceeds the criteria, the process proceeds to step S105. The measurement of the amount of fume F may be performed before or during the fabrication process.

[0044] In step S108, measures are taken to address the fumes F in the vicinity of the area irradiated by the laser light. For example, the fumes F in the vicinity of the area irradiated by the laser light are removed. For example, the fumes F are removed by sucking them out from the suction port 71 using the fume suction mechanism 7C in the modified second embodiment described later. After the measures are taken, the process returns to step S107, and step S108 is repeated until the measured value falls below the standard amount.

[0045] As described above, this embodiment provides the following effects and advantages. In this embodiment, the control unit 50 includes a determination unit 51 that determines whether the minimum span length of the molded object M is greater than or equal to a predetermined length determined based on the amount of fume F generated during the molding of the molded object M. This makes it possible to make a preliminary determination of whether the molded object M will be affected by fume during molding based on the minimum span length of the molded object M. Therefore, molding defects due to fume F can be prevented. This ensures sufficient quality of the molded object M.

[0046] Furthermore, in this embodiment, if the determination unit 51 determines no, the amount of fume F is measured because the molding quality may be reduced due to the influence of fumes. When there is one laser 6, the amount of fume F remaining in the chamber 2 affects the molding quality, so the measurement unit 52 measures the amount of fume F remaining in the chamber 2. When there are two or more lasers 6, the amount of high-concentration fumes generated from the area irradiated by the laser light L affects the molding quality, so the measurement unit 52 measures the amount of fume F near the area irradiated by the laser light L. In this way, by measuring the amount of fume F generated during molding, it is possible to confirm in advance whether the generated fume F will affect the molding quality. Also, if the amount of generated fume F exceeds the criteria, fume countermeasures can be taken in advance to prevent the fume F from affecting the molding quality.

[0047] Furthermore, in this embodiment, the recoater 5 is provided with a suction port 71 for sucking up fumes in the chamber 2. Therefore, when the recoater 5 reciprocates within the chamber 2 during powder laying after each layer is fabricated, the suction port 71 can suck up fumes F in the chamber 2. This keeps the inside of the chamber 2 clean. Consequently, it is possible to prevent fumes F from directly interfering with the laser 6 during fabrication, thereby ensuring fabrication quality.

[0048] [Second Embodiment] A second embodiment of this disclosure will be described below with reference to Figure 6. In this embodiment, only the parts that differ from the first embodiment will be described, and other overlapping parts will not be described. Also, components that are the same as those in the first embodiment will be denoted by the same reference numerals, and their redundant descriptions will be omitted.

[0049] The additive manufacturing apparatus 1B of this embodiment differs from the fume suction mechanism 7A of the first embodiment in the configuration of the fume suction mechanism 7B. The fume suction mechanism 7B comprises a suction port 71, a suction pipe 72, a connecting member 76, a pump 73, and a measuring instrument 74. After each layer is formed, the fume suction mechanism 7B removes the fumes F remaining in the sealed space S by sucking them up with the suction port 71.

[0050] The suction port 71 is located at any point within the chamber 2. A suction tube 72 is connected to the suction port 71, and the suction tube 72 is provided to penetrate the side wall of the chamber 2 from the inside to the outside. A movable mechanism 77 is provided on the portion of the suction tube 72 that is on the inside side of the chamber 2. The movable mechanism 77 is made up of an articulated tube and is configured to move the suction port 71 to any position within the chamber 2.

[0051] A connecting member 76 is provided at the point where the suction pipe 72 penetrates the side wall of the chamber 2 on the gas inlet 22 side. The connecting member 76 houses a drive mechanism (actuator, etc.) not shown that drives the moving mechanism 77. The pump 73 and measuring instrument 74 are the same as in the first embodiment, so their description is omitted.

[0052] (Modified version of the second embodiment) This embodiment can be modified as follows. In Figure 6, the connecting member 76 is provided on the side wall of the chamber 2 on the gas inlet 22 side, but it may be modified as shown in the additive manufacturing apparatus 1C in Figure 7. That is, as shown in the fume suction mechanism 7C in Figure 7, the connecting member 76 may be provided on the side wall of the chamber 2 on the gas outlet 23 side. By doing so, the suction port 71 can be easily accessed to the vicinity of the fume F generated from the laser beam L irradiation area. This makes it possible to suction high-concentration fume F in the vicinity of the area irradiated by the laser beam.

[0053] As described above, this embodiment provides the following effects and advantages. The additive manufacturing apparatus 1B of this embodiment is equipped with a suction port 71 for sucking up fumes F inside the chamber 2. Therefore, fumes F inside the chamber 2 can be sucked up by the suction port 71. This allows the inside of the chamber 2 to be kept clean. In particular, by providing the suction port 71 in areas where there is a risk of fumes F accumulating, fumes F can be efficiently sucked up and removed, and the time required for suction removal can be shortened. Therefore, it is possible to prevent fumes F from directly interfering with the laser 6 during molding, and the molding quality can be ensured.

[0054] Furthermore, this embodiment includes a measuring instrument 74 for measuring the amount of fume F supplied from the suction port 71. This allows monitoring of the amount of fume F accumulating in the chamber 2. If the monitoring results indicate that the accumulated fume F has not been completely removed, the fume F is suctioned multiple times until the amount of fume F falls below a standard amount. In this way, by monitoring the amount of fume F, it is possible to confirm whether the suction is sufficient and to reliably remove the accumulated fume F.

[0055] In this embodiment, by providing a moving mechanism 77 for moving the suction port 71, the suction port can be precisely moved to locations where there is a risk of fume F accumulating, and the fume F can be aspirated. Therefore, the time required for aspiration removal can be shortened. Furthermore, the moving mechanism 77 allows the suction port 71 to be moved to locations within the chamber 2 where fume F accumulates and to locations near the area irradiated by the laser beam L. Since the amount of fume F at both of these locations can be measured by providing the moving mechanism 77, this is particularly suitable when using two or more lasers 6.

[0056] In this embodiment, the suction port 71 is configured to be movable within the chamber 2, but it may also be fixed within the chamber 2. In this case, by fixing the suction port 71 to a location within the chamber 2 where fume F is expected to accumulate, it becomes possible to remove the fume F efficiently.

[0057] [Third Embodiment] A third embodiment of this disclosure will be described below with reference to Figure 8. In this embodiment, only the parts that differ from the first embodiment will be described, and other overlapping parts will not be described. Also, components that are the same as those in the first embodiment will be denoted by the same reference numerals, and their redundant descriptions will be omitted.

[0058] The additive manufacturing apparatus 1D of this embodiment differs from the fume suction mechanism 7A of the first embodiment in the configuration of the fume suction mechanism 7D. The fume suction mechanism 7D comprises a suction port 78, a suction pipe 72, a pump 73, and a measuring instrument 74. The fume suction mechanism 7D removes fumes F that remain in the sealed space S after each layer is fabricated by sucking them out through the suction port 78.

[0059] The suction port 78 is provided on the side wall of the chamber 2. The suction port 78 opens laterally within the chamber 2. The suction port 78 is larger than the suction port 71 of the first and second embodiments. A suction tube 72 is connected to the suction port 78. The pump 73 and measuring instrument 74 are the same as in the first embodiment, so their description is omitted.

[0060] In this embodiment, a protective mechanism 8 is provided within the chamber 2 that can protect the powder P placed in the chamber 2 from suction by the suction port 78. The protective mechanism 8 covers the entire surface of the powder P placed on the material supply stage 31 and the powder P (and the molded object M) placed on the additive manufacturing stage 41. In this way, the protective mechanism 8 protects the area in the chamber 2 where the powder P is laid while waiting for laser 6 irradiation at the time when the molding of each layer is completed.

[0061] The protective mechanism 8 is movable within the chamber 2 by a drive mechanism (not shown). After each layer is formed, the protective mechanism 8 moves to a position that covers the surface of the powder P, and after the fume F is sucked up, it retracts from the position that covers the surface of the powder P before the molding begins.

[0062] As described above, this embodiment provides the following effects and advantages. In the additive manufacturing apparatus 1D of this embodiment, a suction port 78 for sucking up fumes F is provided on the side wall of the chamber 2. Therefore, fumes F inside the chamber can be sucked up by the suction port 78. This allows the inside of the chamber 2 to be kept clean. Consequently, it is possible to prevent fumes F from directly interfering with the laser 6 during molding, and thus ensure molding quality.

[0063] Furthermore, this embodiment includes a measuring instrument 74 for measuring the amount of fume F supplied from the suction port 78. This allows monitoring of the amount of fume F accumulating in the chamber 2. If the monitoring results indicate that the accumulated fume F has not been completely removed by suction, the fume F is suctioned multiple times until the amount of fume F falls below a standard amount. In this way, by monitoring the amount of fume F, it is possible to confirm whether the suction is sufficient and to reliably remove the accumulated fume F.

[0064] Furthermore, this embodiment includes a protective mechanism 8 that is movably provided within the chamber 2 and capable of protecting the powder P placed within the chamber 2 from suction from the suction port 78. This allows the area where the powder P is laid to be protected from suction during fume suction by the protective mechanism 8. Consequently, the suction force during fume suction can be increased, making it possible to remove fumes F more efficiently in a shorter amount of time.

[0065] In this embodiment, one example described is a configuration in which two protective mechanisms 8 are provided: one protective mechanism 8 covering the powder P placed on the stage 31 and another protective mechanism 8 covering the powder P placed on the additive manufacturing stage 41. However, it is also possible to provide a single protective mechanism 8 that covers both the powder P placed on the stage 31 and the powder P placed on the additive manufacturing stage 41.

[0066] <Note> The additive manufacturing apparatus and additive manufacturing method described in the embodiments above can be understood, for example, as follows.

[0067] An additive manufacturing apparatus (1A) according to a first aspect of the present disclosure comprises a chamber (2) that forms a sealed space (S), a stage (41) provided in the chamber on which powder (P), which is the raw material for an object (M) manufactured by additive manufacturing, is placed, at least one laser (6) that irradiates the powder with laser light (L), and a control unit (50) that controls the laser, wherein the control unit includes a determination unit (51) that determines whether the minimum screen length of the object is greater than or equal to a predetermined length determined based on the amount of fume (F) generated during the manufacturing of the object.

[0068] When creating a material by irradiating powder with laser light, fumes (metal vapors) are generated. If a large amount of fumes are generated, the quality of the laser light deteriorates in proportion to the amount of fumes. Specifically, the laser output decreases and the beam diameter increases. This reduces the heat input energy density, making the penetration depth unstable and increasing the probability of defects. In particular, since the laser light does not reach the set output immediately after oscillation but gradually approaches the set value, the penetration depth tends to be unstable immediately after oscillation. Therefore, even under optimal conditions that result in fewer defects (usually an output of several hundred watts and a scanning speed of several hundred to several thousand mm / s) when the canvas length is short, the penetration depth becomes unstable. In this case, the instability is further exacerbated by the influence of fumes.

[0069] On the other hand, in this disclosure, the control unit includes a determination unit that determines whether the minimum span length of the molded object is greater than or equal to a predetermined length determined based on the amount of fume generated during the molding of the object. This makes it possible to make a preliminary determination from the minimum span length of the molded object whether or not it will be affected by fume during molding. Therefore, molding defects due to fume can be prevented. This ensures sufficient quality of the molded product.

[0070] In the first embodiment, the additive manufacturing apparatus according to a second aspect of the present disclosure includes a control unit (52) which measures the amount of fume accumulating in the chamber when there is one laser, and measures the amount of fume near the portion of the chamber irradiated by the laser light when there are two or more lasers, and the measurement unit measures the amount of fume when the determination unit determines no.

[0071] In this disclosure, if the determination unit determines that the material quality may be reduced due to the influence of fumes, the amount of fumes is measured. When there is one laser, the amount of fumes remaining in the chamber affects the material quality, so the measurement unit measures the amount of fumes remaining in the chamber. When there are two or more lasers, the amount of high-concentration fumes generated from the area irradiated by the laser light affects the material quality, so the measurement unit measures the amount of fumes near the area irradiated by the laser light. In this way, by measuring the amount of fumes generated during material creation, it is possible to confirm in advance whether the generated fumes will affect the material quality. Furthermore, if the amount of generated fumes exceeds the criteria, it is possible to prevent fumes from affecting the material quality by implementing fume control measures in advance.

[0072] An additive manufacturing apparatus according to a third aspect of the present disclosure comprises, in the first or second aspect, a recoater (5) provided in the chamber and supplying the powder to the upper surface of the stage; a suction port (71) provided in the recoater for sucking up the fume in the chamber; a pump (73) connected to the suction port and applying suction force to the suction port; and a measuring instrument (74) connected to the pump and measuring the amount of the fume supplied from the suction port.

[0073] In this disclosure, the recoater is provided with a suction port for sucking up fumes from inside the chamber. Therefore, when the recoater moves back and forth inside the chamber during powder laying after each layer is fabricated, fumes from inside the chamber can be sucked up by the suction port. This keeps the inside of the chamber clean. Consequently, it is possible to prevent fumes from directly interfering with the laser during fabrication and ensure fabrication quality.

[0074] Furthermore, this disclosure includes a measuring instrument for measuring the amount of fume supplied from the suction port. This allows monitoring of the amount of fume accumulating in the chamber. If the monitoring results indicate that the accumulated fume has not been completely aspirated, the recourer is moved back and forth multiple times until the amount of fume falls below a standard amount to aspirate the fume. In this way, by monitoring the amount of fume, it is possible to confirm whether the suction is sufficient and to reliably remove the accumulated fume.

[0075] An additive manufacturing apparatus (1B) according to a fourth aspect of the present disclosure comprises, in the first or second aspect, a suction port provided in the chamber for sucking up the fume in the chamber; a pump connected to the suction port for applying suction force to the suction port; and a measuring instrument connected to the pump for measuring the amount of the fume supplied from the suction port.

[0076] This disclosure provides a suction port for aspirating fumes within the chamber. Therefore, fumes inside the chamber can be aspirated using the suction port. This allows the inside of the chamber to be kept clean. In particular, by providing the suction port in areas where there is a risk of fume accumulation, fumes can be efficiently aspirated and removed, and the time required for aspiration and removal can be reduced. Therefore, it is possible to prevent fumes from directly interfering with the laser during the molding process and to ensure molding quality.

[0077] Furthermore, this disclosure includes a measuring instrument for measuring the amount of fume supplied from the suction port. This allows monitoring of the amount of fume accumulating in the chamber. If the monitoring results indicate that the accumulated fume has not been completely removed by suction, the fume is suctioned multiple times until the amount of fume falls below a standard amount. In this way, by monitoring the amount of fume, it is possible to confirm whether the suction is sufficient and to reliably remove the accumulated fume.

[0078] An additive manufacturing apparatus (1C) according to a fifth aspect of this disclosure includes a moving mechanism (77) for moving the suction port, in a fourth aspect.

[0079] This disclosure provides a mechanism for moving the suction port, allowing the suction port to be precisely positioned to areas where fumes are likely to accumulate, thereby enabling fumes to be aspirated. Consequently, the time required for suction removal can be reduced. Furthermore, the suction port can be moved by the mechanism to both areas within the chamber where fumes accumulate and areas near the laser beam. The inclusion of the movement mechanism allows for measurement of the amount of fumes at both of these locations, making it particularly suitable when using two or more lasers.

[0080] An additive manufacturing apparatus (1D) according to a sixth aspect of the present disclosure comprises, in the first or second aspect, a suction port (78) provided on the side wall of the chamber for sucking up the fume in the chamber; a pump connected to the suction port and for applying suction force to the suction port; a measuring instrument connected to the pump and for measuring the amount of the fume supplied from the suction port; and a protective mechanism (8) provided so as to be movable within the chamber and capable of protecting the powder placed in the chamber from suction by the suction port.

[0081] In this disclosure, a suction port for sucking up fumes is provided on the side wall of the chamber. Therefore, fumes inside the chamber can be sucked up by the suction port. This allows the inside of the chamber to be kept clean. Consequently, it is possible to prevent fumes from directly interfering with the laser during the molding process and to ensure molding quality.

[0082] Furthermore, this disclosure includes a measuring instrument for measuring the amount of fume supplied from the suction port. This allows monitoring of the amount of fume accumulating in the chamber. If the monitoring results indicate that the accumulated fume has not been completely removed by suction, the fume is suctioned multiple times until the amount of fume falls below a standard amount. In this way, by monitoring the amount of fume, it is possible to confirm whether the suction is sufficient and to reliably remove the accumulated fume.

[0083] Furthermore, this disclosure includes a protective mechanism that is movably mounted within the chamber and capable of protecting the powder placed within the chamber from suction from the suction port. This allows the area where the powder is laid to be protected from suction during fume suction by the protective mechanism. Consequently, the suction force during fume suction can be increased, enabling more efficient removal of fumes in a shorter time.

[0084] An additive manufacturing method according to a seventh aspect of the present disclosure is an additive manufacturing method using an additive manufacturing apparatus comprising: a chamber forming a sealed space; a stage provided in the chamber on which powder, which is the raw material for an additively manufactured object, is placed; and at least one laser for irradiating the powder with laser light, the method comprising: a determination step of determining whether the minimum screen length of the manufactured object is greater than or equal to a predetermined length determined based on the amount of fume generated during the manufacturing of the manufactured object; and a manufacturing step of irradiating the powder with laser light using the additive manufacturing apparatus to melt and bond the powder and manufacture an object.

[0085] This disclosure includes a determination step that determines whether the minimum span length of the printed object is greater than or equal to a predetermined length determined based on the amount of fume generated during the printing of the object. This makes it possible to make a preliminary determination of whether the printed object will be affected by fume during printing based on the minimum span length of the object. Therefore, it is possible to prevent printing defects caused by fume. This ensures sufficient quality of the printed product. [Explanation of symbols]

[0086] 1A, 1B, 1C, 1D Additive manufacturing equipment 2 Chambers 3 Material supply section 4. Additive Manufacturing Department 5. Recorder 6 lasers 7A,7B,7C,7D Fume suction mechanism 8 Protection mechanism 21 Transparent window 22 Gas Inlet 23 Gas outlet 31 stages 41 stages 50 Control Unit 51 Judgment section 52 Measurement section 71,78 Suction port 72 Suction tube 73 pumps 74 Measuring Instruments 75 Telescopic mechanism 76 Connecting member 77 Moving mechanism F. Hume L Laser light M Modeled object P powder S closed space

Claims

1. A chamber that forms a sealed space, A stage is provided within the chamber on which powder, which is the raw material for the molded object produced by additive manufacturing, At least one laser that irradiates the powder with laser light, A control unit that controls the laser, Equipped with, The control unit comprises a determination unit that determines whether the minimum span length of the molded object is greater than or equal to a predetermined length determined based on the amount of fume generated during the molding of the object.

2. The control unit has a measuring unit that, when there is one laser, measures the amount of fume accumulating in the chamber, and when there are two or more lasers, measures the amount of fume near the portion of the chamber irradiated by the laser light. The additive manufacturing apparatus according to claim 1, wherein the measuring unit measures the amount of fume if the determination unit determines that the result is negative.

3. A recoater provided within the chamber for supplying the powder to the upper surface of the stage, The recoater is provided with a suction port for sucking up the fume in the chamber, A pump connected to the suction port and which applies suction force to the suction port, The additive manufacturing apparatus according to claim 1 or 2, further comprising a measuring instrument connected to the pump and for measuring the amount of fume supplied from the suction port.

4. A suction port is provided inside the chamber for sucking up the fume inside the chamber, A pump connected to the suction port and which applies suction force to the suction port, The additive manufacturing apparatus according to claim 1 or 2, further comprising a measuring instrument connected to the pump and for measuring the amount of fume supplied from the suction port.

5. The additive manufacturing apparatus according to claim 4, further comprising a moving mechanism for moving the suction port.

6. A suction port is provided on the side wall of the chamber for sucking out the fume inside the chamber, A pump connected to the suction port and which applies suction force to the suction port, A measuring instrument connected to the pump and used to measure the amount of fume supplied from the suction port, A protective mechanism is provided so as to be movable within the chamber and capable of protecting the powder placed within the chamber from suction from the suction port, The additive manufacturing apparatus according to claim 1 or 2, comprising:

7. An additive manufacturing method using an additive manufacturing apparatus comprising: a chamber that forms a sealed space; a stage provided inside the chamber on which powder, which is the raw material for an object manufactured by additive manufacturing, is placed; and at least one laser that irradiates the powder with laser light, A determination step of determining whether the minimum span length of the molded object is greater than or equal to a predetermined length determined based on the amount of fume generated during the molding of the object, An additive manufacturing method comprising a molding step of irradiating powder with laser light using the additive manufacturing apparatus to melt and bond the powder and form a molded object.

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