JP7727418B2 - Manufacturing method of layered object and layered manufacturing device - Google Patents

Description

This disclosure relates to a method for manufacturing an additive manufacturing object and an additive manufacturing apparatus.

Known additive manufacturing technologies (metal additive manufacturing) include, for example, powder bed fusion (PBB) and directed energy deposition (DEM). PBB performs additive manufacturing by irradiating a flat layer of metal powder with a light beam (laser beam, electron beam, etc.). Examples of PBB methods include selective laser melting (SLM) and electron beam melting (EBM). DEM performs additive manufacturing by controlling the position of a head that irradiates the light beam and ejects the powder material. Examples of DEM methods include laser metal deposition (LMD) and direct metal deposition (DMP).

The abstract of Patent Document 1 states, "The three-dimensional additive manufacturing device selectively solidifies a powder bed formed by laying powder on a base plate by irradiating the powder bed with a beam. The shape or temperature of the surface of the powder bed or the surface to be built is detected by a sensor, and based on the detection results, any imperfections in the laying of the powder or the irradiation of the beam are corrected before the building of the next layer is completed."

International Publication No. 2019/030839

In additive manufacturing (ML), structural abnormalities such as expansion and deformation can occur due to overheating of the object (heating above a target temperature) caused by irradiation with a light beam. The occurrence of structural abnormalities can cause the ML device to stop unintentionally, for example, during powder bed formation. The technology described in Patent Document 1 simply forms a powder bed on top of detected irregularities (paragraph 0068). Therefore, structural abnormalities such as irregularities can still cause the ML device to stop during powder bed formation.
The problem to be solved by the present disclosure is to provide a method for manufacturing an additive manufacturing object and an additive manufacturing device that can prevent unintended shutdown of the additive manufacturing device.

The method for manufacturing an additively manufactured object according to the present disclosure includes: a predetermined layer forming step of forming a predetermined layer, which is a metal layer, by irradiating a powder bed of a metal material with a light beam; a surface temperature determination step of determining the surface temperature of an intermediate object obtained through the predetermined layer forming step; a determination step of determining whether the intermediate object is in an overheated state based on the surface temperature and a predetermined threshold value indicating an overheated state of the intermediate object; and a powder bed forming step of forming the powder bed on the predetermined layer when it is determined that the intermediate object is not in an overheated state as a result of the determination step. In the determination step, it is determined that the intermediate object is not in an overheated state when the surface temperature is equal to or lower than the predetermined threshold value, and the surface temperature is at least the surface temperature of a portion that is likely to accumulate heat, which is predetermined based on the structure of the additively manufactured object to be manufactured . Other solutions will be described later in the detailed description of the invention.

This disclosure provides a method for manufacturing an additive manufacturing object and an additive manufacturing device that can prevent unintended shutdowns of the additive manufacturing device.

1 is a flowchart showing a method for manufacturing a layered object according to the first embodiment. 1 is a structural diagram showing an additive manufacturing apparatus according to a first embodiment; 1 is a block diagram showing an additive manufacturing apparatus according to a first embodiment; FIG. 10 is a perspective view illustrating a portion of the shaped object where heat is likely to accumulate. 4B is a cross-sectional view taken along line AA in FIG. 4A. 4C is a cross-sectional view taken along line BB in FIG. 4B, and is a cross-sectional view taken in the direction of movement of the light beam during additive manufacturing. 10 is a flowchart showing a method for manufacturing a layered object according to a second embodiment. 10 is a flowchart showing a method for manufacturing a layered object according to a third embodiment. FIG. 10 is a structural diagram showing a layered manufacturing apparatus according to a third embodiment. FIG. 10 is a block diagram showing an additive manufacturing apparatus according to a third embodiment. 10 is a flowchart showing a method for manufacturing a layered object according to a fourth embodiment. FIG. 10 is a structural diagram showing a layered manufacturing apparatus according to a fourth embodiment. FIG. 10 is a block diagram showing a layered manufacturing apparatus according to a fourth embodiment. 13 is a flowchart showing a method for manufacturing a layered object according to a fifth embodiment. FIG. 10 is a structural diagram showing a layered manufacturing apparatus according to a fifth embodiment. FIG. 10 is a block diagram showing an additive manufacturing apparatus according to a fifth embodiment. 13 is a flowchart showing a method for manufacturing a layered object according to a sixth embodiment. 13A to 13C are diagrams illustrating the operation of a recoater when using the manufacturing method of the sixth embodiment. 13 is a flowchart showing a method for manufacturing a layered object according to a seventh embodiment. 19 is a flowchart showing a method for manufacturing a layered object according to the eighth embodiment. FIG. 19 is a block diagram showing an additive manufacturing apparatus according to an eighth embodiment. FIG. 2 is a block diagram illustrating a hardware configuration of a control device.

Below, modes for implementing the present disclosure (hereinafter referred to as "embodiments") will be described with reference to the drawings. Within the description of one embodiment below, other embodiments that are applicable to the first embodiment will also be described as appropriate. The present disclosure is not limited to the single embodiment below, and different embodiments can be combined or modified as desired without significantly impairing the effects of the present disclosure. Furthermore, the same components will be given the same reference numerals, and duplicate descriptions will be omitted. Furthermore, components having the same functions will be given the same names. The contents shown are merely schematic, and for the sake of illustration, the actual configuration may be changed, and some components may be omitted or modified between drawings, within the scope of not significantly impairing the effects of the present disclosure.

Figure 1 is a flowchart showing a method for manufacturing an additively manufactured object R (Figure 4) according to the first embodiment (hereinafter referred to as the manufacturing method according to the first embodiment). The manufacturing method according to the first embodiment is a method for manufacturing an additively manufactured object R (Figure 4A) by irradiating a light beam L (Figure 2) onto a powder bed PB (Figure 2) in which powder P of a metal material is arranged (spread) in layers. The manufacturing method according to the first embodiment includes steps S1 to S6. For convenience, an additively manufactured object 300 capable of carrying out the manufacturing method according to the first embodiment will first be described with reference to Figures 2 and 3.

Figure 2 is a structural diagram showing the additive manufacturing device 300 of the first embodiment. The additive manufacturing device 300 is a device that manufactures an additively manufactured object R by additive manufacturing, and includes a manufacturing device main body 100, a temperature sensor 13, and a control device 200.

The modeling device main body 100 forms a metal layer 507 (Figure 4B) by irradiating a powder bed PB of metal material with a light beam L, and is a modeling device that uses the powder bed fusion method. The modeling device main body 100 irradiates the powder bed PB with a light beam L (laser beam, electron beam, etc.) to heat the powder P, causing it to melt and solidify. The metal layer is formed by repeatedly laying down the powder P and irradiating it with the light beam L.

In this disclosure, the additive manufacturing object R is the object to be manufactured by repeatedly forming the metal layer 507, and the additive manufacturing object R is in the middle of its manufacturing process (when only some of the metal layers 507 of the multiple metal layers that make up the additive manufacturing object R have been formed) is the intermediate body S (object intermediate). In this disclosure, the additive manufacturing device 300 will be described mainly using the intermediate body S as an example.

The powder P is not particularly limited, but examples include powders of metal materials such as hot work tool steel, copper, titanium alloy, nickel alloy, aluminum alloy, cobalt chromium alloy, and stainless steel. In the present disclosure, for example, a metal material having an average particle size of approximately 30 μm and a particle size range of approximately 15 μm to approximately 45 μm is used as the powder P. The average particle size of the powder P is not limited to the above range.

The modeling device main body 100 forms a predetermined layer, which is a metal layer 507, by irradiating the powder bed PB with a light beam L. The modeling device main body 100 includes, for example, a chamber 10, a gas supply unit 20, an exhaust mechanism 30, a material supply unit 40, a modeling unit 50, a recovery unit 60, a recoater (squeegee) 70, and a beam source 80. In addition, in the illustrated example, the temperature sensor 13 provided in the additive manufacturing device 300 is provided in the modeling device main body 100.

The chamber 10 houses, for example, all parts of the modeling apparatus main body 100 except for the beam source 80 and the exhaust mechanism 30. The chamber 10 has, for example, a transmission window 12 fitted with protective glass 12g. The transmission window 12 transmits the light beam L emitted from the beam source 80 located outside the chamber 10, allowing it to reach the powder bed PB placed on the stage 51 of the modeling unit 50 inside the chamber 10.

The molding apparatus main body 100 is equipped with a temperature sensor 13, a pressure sensor 14, and an oxygen sensor 15. The temperature sensor 13 determines the surface temperature of the intermediate body S. The surface temperature is, for example, the temperature of the upper surface of the intermediate body S, which is the surface irradiated with the light beam L. The temperature sensor 13 is, for example, a non-contact temperature sensor, and more specifically, an infrared radiation thermometer or the like. The pressure sensor 14 and oxygen sensor 15 measure the pressure and oxygen amount (oxygen concentration) of the reduced pressure environment within the chamber 10, respectively.

The gas supply unit 20 is connected to the chamber 10 and supplies an inert gas to the interior of the chamber 10. The gas supply unit 20 includes, for example, a gas supply source and a control valve (neither of which are shown). The gas supply source is composed of a high-pressure tank (not shown) filled with an inert gas. The control valve is controlled by the control device 200 and controls the flow rate of the inert gas supplied from the gas supply source to the chamber 10. The inert gas can be, for example, nitrogen or argon.

The exhaust mechanism 30 is, for example, a vacuum pump, and is connected to the chamber 10 via a vacuum piping 31. The exhaust mechanism 30 is, for example, controlled by the control device 200. By using the exhaust mechanism 30 to exhaust gas from the chamber 10, the interior of the chamber 10 can be made to have a vacuum pressure lower than atmospheric pressure, creating a reduced pressure environment inside the chamber 10.

The material supply unit 40 is, for example, recessed and open at the top to accommodate the powder P. The material supply unit 40 has a stage 41 that can move up and down on which the powder P is placed and supplied. The stage 41 forms the bottom wall of the material supply unit 40. The stage 41 is arranged so that it can be raised and lowered at a predetermined pitch, for example, by an appropriate lifting mechanism (not shown). The lifting mechanism for the stage 41 is connected to and controlled by the control device 200, for example. The material supply unit 40 may not be of the lifting type as shown, but may instead be of a type that drops the powder P to supply it.

The modeling unit 50, like the material supply unit 40, is a concave storage unit capable of storing powder P (metal material) and intermediate body S, and is open at the top with an opening at the top end. The modeling unit 50 has a stage 51 for spreading powder P to form a powder bed PB. The stage 51 is made of metal, for example, and forms the bottom wall of the modeling unit 50. The powder P supplied from the material supply unit 40 is placed on the stage 51 (support member), and the intermediate body S manufactured by additive manufacturing is supported via a metal bond.

The opening of the modeling unit 50 and the opening of the material supply unit 40 are, for example, approximately equal in vertical height and aligned approximately horizontally. Like the stage 41, the stage 51 is configured to be able to move up and down at a predetermined pitch, for example, by an appropriate lifting mechanism (not shown). The stage 51 may also be equipped with a preheating mechanism (not shown) that includes a heater for preheating the stage 51. The lifting mechanism and preheating mechanism of the stage 51 are connected to, for example, the control device 200 and are controlled by the control device 200.

The recovery unit 60, similar to the material supply unit 40, is recessed and capable of containing powder P, with an open top and an opening at the top. In the illustrated example, the bottom wall of the recovery unit 60 is fixed to the lower end, but similar to the material supply unit 40 and the modeling unit 50, it may be formed by a stage (not shown) that can be raised and lowered. The opening of the recovery unit 60 and the opening of the modeling unit 50 are roughly equal in vertical height and aligned roughly horizontally. The recovery unit 60 contains and recovers excess powder P supplied from the material supply unit 40 to the modeling unit 50 by, for example, the recoater 70.

The recoater 70 (powder supply mechanism) carries the powder P supplied from the material supply unit 40 onto the stage 51 of the modeling unit 50 and spreads it evenly, forming a powder bed PB on the stage 51. The recoater 70 is equipped with, for example, a movement mechanism 75 (powder supply mechanism). The movement mechanism 75 is, for example, a linear motor, and moves the recoater 70 along a generally horizontal traveling direction D from the material supply unit 40 toward the modeling unit 50.

The beam source 80 can be, for example, a laser light source that generates a light beam L with an output of several watts to several kilowatts. In the present disclosure, for example, a single-mode fiber laser with a wavelength of 1080 nm and an output of 500 W, i.e., a laser light source that generates a laser with a Gaussian energy intensity distribution, is used. The beam source 80 also includes, for example, a galvanometer scanner (not shown) for scanning the light beam L over the powder bed PB.

Figure 3 is a block diagram showing the additive manufacturing device 300 of the first embodiment. The control device 200 includes a determination unit 21 and a manufacturing control unit 22. The specific hardware configuration of the control device 200 will be described later with reference to Figure 20.

The determination unit 21 determines whether the intermediate S is in an overheated state based on the surface temperature of the intermediate S determined by the temperature sensor 13 (Figure 1) and a predetermined threshold value indicating an overheated state of the intermediate S. Furthermore, the modeling control unit 22 controls the modeling apparatus main body 100 to start forming the next metal layer 507 (Figure 4B) when the determination unit 21 determines that the intermediate S is not in an overheated state. The formation is performed by irradiating a light beam L onto the powder bed PB on the metal layer 507, which is the top surface of the intermediate S. The specific functions of the determination unit 21 and the modeling control unit 22 will be explained with reference to Figure 1 again.

Step S1 (predetermined layer formation step) is a step in which a predetermined layer, which is a metal layer 507, is formed by irradiating the powder bed PB with a light beam L. The irradiation is stopped after each metal layer 507 is formed. Step S1 can be executed by the modeling control unit 22 (Figure 2). When forming the first layer, the predetermined layer is formed on the upper surface of the stage 51 (Figure 2). When forming the second or subsequent layer, the predetermined layer is formed one layer above the metal layer 507 that was formed immediately before.

After forming the predetermined layers, the modeling control unit 22 (Figure 2) determines whether to continue modeling (step S2). Since the intermediate body S usually has multiple layers, when the first layer is formed in step S1, modeling continues to form the second and subsequent layers (Y). On the other hand, when the intermediate body S that is the target of modeling is obtained in step S1, that is, when the final metal layer 507 (Figure 4B) is formed, modeling ends (N).

Step S3 (surface temperature determination step) is a step for determining the surface temperature of the intermediate body S obtained through step S1. Step S3 can be executed by the judgment unit 21 (Figure 2). In the first embodiment, the determined surface temperature is at least the surface temperature of a portion where heat is likely to accumulate, which is determined in advance based on the structure of the additive manufacturing object R (Figure 4A) to be manufactured. Overheating is likely to occur in portions where heat is likely to accumulate, and structural abnormalities such as expansion and deformation due to overheating are likely to occur. Therefore, by determining at least the surface temperature of the portion where heat is likely to accumulate, overheating in such portions can be suppressed, and the occurrence of structural abnormalities can be suppressed. Note that suppressing overheating here does not mean restricting overheating to no overheating at all, but rather means allowing overheating to a degree that, even if overheating occurs and structural abnormalities occur, the structural abnormalities are alleviated (preferably return to normal) as the temperature drops.

Figure 4A is a perspective view illustrating parts of the additively-shaped object R where heat is likely to accumulate. The additively-shaped object R shown in Figure 4A is an example of an additively-shaped object that can be additively manufactured using the additive manufacturing device 300, and the structure of the additively-shaped object R is not limited to the example shown. Note that, for simplicity of illustration, Figure 4A and Figure 4B described below only show a portion of the metal layer 507 formed by additive manufacturing. In the illustrated example, the additively-shaped object R is an additively-shaped object having spaces 501, 504, 506, 508, and 509.

Figure 4B is a cross-sectional view taken along line A-A in Figure 4A. The additive manufacturing object R has a structure in which metal layers 507 are continuously arranged in the z direction. In the cross-sectional view shown in Figure 4B, spaces 501 and 504 have a parallelogram shape. Spaces 506 and 508 have a circular shape. During additive manufacturing, powder P of metal material remains inside spaces 501, 504, 506, and 508. During additive manufacturing, for example, a powder bed PB (Figure 2) exists below metal layer 503 (a predetermined layer; an example of metal layer 507) including upper edge 502 (section C) that defines space 501. This shape is called an overhang shape.

Overheating occurs due to heat retention. For this reason, if a heat transfer path to the metal layer 507, for example to the stage 51 below, is secured, heat is less likely to accumulate. However, in the powder bed PB made of powder P (Figure 2), heat transfer is less likely to occur than in the additive manufacturing object R made of solids alone due to the presence of gaps between the powder P. Therefore, the heat transfer path in the specified layer 503 is limited, making it easier for heat to accumulate. For this reason, in the first embodiment, the surface temperature of the portion of the additive manufacturing object R where there is space below the metal layer 503 (the powder bed PB during additive manufacturing) is determined.

Figure 4C is a cross-sectional view taken along line B-B in Figure 4B, in the direction of movement of the light beam L during additive manufacturing. Figure 4C is a cross-sectional view taken directly above the metal layer 505 in Figure 4B, viewed in the -z direction. The additively manufactured object R has a space 509 extending in the x direction. As shown in Figures 4B and 4C above, for example, space 501 extends from the upper right to the lower left, and as shown in part D, the heat transfer path formed between the outer surface of the manufactured additive object R and space 501 becomes small. This makes it easy for heat to accumulate and overheat. Therefore, in the first embodiment, the surface temperature is further determined for the portion of the metal layer 505 (a predetermined layer; an example of a metal layer 507) whose cross-sectional area shown in Figure 4C is equal to or less than a predetermined area.

As such, in the example disclosed herein, the portions where heat is likely to accumulate include at least one of the following: portions of the metal layer 503 in the additively-shaped object R where there is space below (for example, the edge portions of the additively-shaped object R); or portions of the metal layer 505 where the cross-sectional area in the direction of movement of the light beam L during additive manufacturing (x and y directions in the illustrated example) is equal to or less than a predetermined area. This makes it possible to determine the surface temperature of portions where overheating is likely to occur in a concentrated manner, and makes it particularly effective to suppress structural abnormalities caused by overheating.

Returning to Figure 1, step S3 (determination step) is a step in which it is determined whether the intermediate S is in an overheated state based on the surface temperature determined in step S2 and a predetermined threshold value indicating whether the intermediate S is in an overheated state. Step S3 can be executed by the determination unit 21 (Figure 2). The predetermined threshold value can be determined, for example, based on the thermal expansion coefficient of the metal material used. Specifically, as just one example, the amount of expansion (e.g., length) at a predetermined elevated temperature can be determined from the thermal expansion coefficient. Therefore, the amount of expansion that is unacceptable when overheated can be determined, and the temperature corresponding to that amount of expansion can be set as the predetermined threshold value.

The predetermined threshold value differs, for example, for each metal layer 507 (Figure 4B) in the intermediate body S. Even if the amount of expansion is acceptable for each metal layer 507, the accumulation of that expansion may result in an unacceptable amount of expansion overall. However, even in such cases, by changing the predetermined threshold value for each metal layer 507, it is possible to suppress the amount of expansion to an acceptable level overall.

In step S3 of the first embodiment, when the surface temperature of the portion prone to overheating falls below the predetermined threshold, it is determined that the portion is not in an overheated state. In other words, if the surface temperature falls below the predetermined threshold, the amount of expansion in the portion prone to overheating is reduced, and the occurrence of structural abnormalities is suppressed. Therefore, in this case, even if the surface temperature exceeds the predetermined threshold and is determined to be an overheated state, it can be determined that the portion is not in an overheated state if it falls below the predetermined threshold, and the occurrence of structural abnormalities during the subsequent formation of the metal layer 507 can be suppressed.

If the result of the judgment in step S4 is that the device is not in an overheated state (Y), step S5 is performed; if the result is that the device is in an overheated state (N), step S6 is performed.

Step S5 (powder bed formation step) is a step in which a powder bed PB (Figure 2) is formed on a predetermined layer whose surface temperature has been determined. Formation of the powder bed PB can be performed, for example, by driving the recoater 70 (Figure 2) to supply powder P to the modeling unit 50. Step S5 can be performed, for example, by the modeling control unit 22 (Figure 3). After the powder bed PB is formed, the above-mentioned step S1 is performed again.

Step S6 (waiting step) is a step in which, when it is determined in step S4 that the intermediate body S is in an overheated state, the intermediate body S waits until it is no longer in an overheated state. Step S6 reduces the surface temperature of the intermediate body S, making it no longer overheated. In the first embodiment, step S6 is performed, for example, by natural cooling, and the surface temperature can be reduced by dissipating heat from the intermediate body S through natural cooling.

The standby in step S6 is performed by repeating the determination of the surface temperature and the determination of the overheated state, for example, at predetermined intervals, in the same manner as in steps S3 and S4 above. During standby, the light beam L is not irradiated. Then, when it is determined that the overheated state is not present, step S5 is performed.

According to the first embodiment described above, even if the intermediate body S (particularly the predetermined layer, which is the uppermost metal layer 507) is in an overheated state, the occurrence of structural abnormalities due to the overheated state can be suppressed by waiting until the overheated state is no longer present before forming the powder bed PB. This makes it possible to suppress unintended shutdowns of the additive manufacturing apparatus 300 (Figure 2), for example, during powder bed formation. This allows the continuous use time of the additive manufacturing apparatus 300 to be extended, improving manufacturing efficiency.

Figure 5 is a flowchart showing a method for manufacturing a layered object R (Figure 4A) according to a second embodiment (hereinafter referred to as the manufacturing method according to the second embodiment). The manufacturing method according to the second embodiment is the same as the manufacturing method according to the first embodiment, except that it includes step S31 instead of step S3 (Figure 1). Step S31 is the same as step S3, except that the target for determining the surface temperature is different.

The surface temperature determined in step S31 (surface temperature determination step) is the surface temperature of the entire upper surface of the intermediate body S. The entire upper surface is, for example, the entire metal layer 507 (an example of a predetermined layer) formed on the top surface. By basing the surface temperature of the entire upper surface on the surface temperature, it is possible to omit the step of determining areas where heat is likely to accumulate, as in the first embodiment, and control can be simplified. As described above, with the intermediate body S, heat is likely to accumulate at the edge portion (the boundary portion with the powder P) of the layered object R (Figure 4A). For this reason, the temperature tends to rise along the edge, and the temperature sensor 13 can determine the area of the entire upper surface of the intermediate body S.

The determination of whether or not the device is in an overheated state may be made when the surface temperature across the entire upper surface falls below a predetermined threshold, or by comparing the average surface temperature across the entire upper surface with the predetermined threshold. When comparing with the average value, it is preferable to change the predetermined threshold for comparison with the average value.

Figure 6 is a flowchart showing a method for manufacturing a layered object R (Figure 4A) according to a third embodiment (hereinafter referred to as the manufacturing method of the third embodiment). The manufacturing method of the third embodiment is similar to the manufacturing method of the first embodiment, except that it includes step S61 instead of step S6 (Figure 1) described above.

Step S61 (cooling step) is a step in which the surface temperature is lowered by cooling the intermediate body S for at least a portion (preferably the entirety) of the time from step S4 (determination step) to step S5 (powder bed formation step). Specific cooling methods will be described later with reference to Figures 7 and 8. Step S61 allows the surface temperature to be lowered more quickly than natural cooling, improving the manufacturing efficiency of the additive manufacturing device 301 (Figure 7). An additive manufacturing device 301 capable of executing step S61 will be described with reference to Figures 7 and 8.

Figure 7 is a structural diagram showing an additive manufacturing apparatus 301 of the third embodiment. The additive manufacturing apparatus 301 is similar to the additive manufacturing apparatus 300 (Figure 2), except that it includes a modeling apparatus main body 101 instead of the modeling apparatus main body 100 (Figure 2). The modeling apparatus main body 101 is similar to the modeling apparatus main body 100 (Figure 2), except that it further includes a cooling mechanism 52.

The cooling mechanism 52 is installed on at least one of the sidewall 53 or the stage 51 (support member) of the molding unit 50, and cooling is performed by installing the cooling mechanism 52 on at least one of the sidewall 53 or the stage 51. In the example shown, the cooling mechanism 52 is installed on both the sidewall 53 and the stage 51. The cooling mechanism 52 includes, for example, at least one of a water cooling device, an air cooling device, or a heat sink. In the example shown, the cooling mechanism 52 is a water cooling device, and a water flow space 54 through which cooling water (not shown) flows is provided inside the sidewall 53 and the stage 51. The water flow space 54 is, for example, a water pipe.

Figure 8 is a block diagram showing an additive manufacturing apparatus 301 according to a third embodiment. Figure 8 shows a case in which at least one of a water-cooling device and an air-cooling device is used as the cooling mechanism 52. Step S61 (Figure 6) can be executed by the control of the cooling mechanism 52 by the manufacturing control unit 22.

When the cooling mechanism 52 is, for example, a water cooling device, the cooling mechanism 52 includes, for example, a water passage space 54 (FIG. 7) and a pump (not shown) that generates a water flow into the water passage space 54. The forming control unit 22 can achieve particularly efficient cooling by, for example, controlling the amount of water passed by the pump in accordance with the surface temperature of the intermediate body S. Note that the temperature of the cooling water may be controlled instead of or in addition to controlling the pump.

When the cooling mechanism 52 is, for example, an air-cooling device, the cooling mechanism 52 includes, for example, a ventilation space (not shown, e.g., piping) through which gas (e.g., air) flows, and a fan (not shown) that generates an airflow into the ventilation space. The forming control unit 22 can achieve particularly efficient cooling, for example, by controlling the amount of airflow by the fan according to the surface temperature of the intermediate body S. Note that instead of or in addition to controlling the fan, the temperature of the gas flowing into the ventilation space may be controlled.

Returning to FIG. 6, as described above, cooling in step S61 is performed by cooling at least one of the sidewalls 53 ( FIG. 7 ) or the stage 51 ( FIG. 7 ) (both in the illustrated example). Because the sidewalls 53 and the stage 51 are arranged to define the molding section 50 ( FIG. 7 ), cooling at least one of them can effectively cool the intermediate body S housed in the molding section 50. In particular, cooling the stage 51 makes it easier to dissipate heat from the intermediate body S, which is metallurgically bonded to the stage 51, to the stage 51 via this metallurgical bond. Furthermore, cooling the sidewalls 53 allows effective cooling when the width (length in the xy plane shown in FIG. 4A ) of the intermediate body S increases and it approaches the sidewalls 53, even when it is far from the stage 51.

Figure 9 is a flowchart showing a method for manufacturing a layered object R (Figure 4A) according to the fourth embodiment (hereinafter referred to as the manufacturing method of the fourth embodiment). The manufacturing method of the fourth embodiment is similar to the manufacturing method of the first embodiment, except that it further includes step S7.

Step S7 (support member temperature determination step) is a step for determining the temperature of the stage 51 (support member). Step S7 determines the temperature of the stage 51, and the temperature of the stage 51 can be used for the control described below. Step S7 is performed, for example, between steps S2 and S4, and in the illustrated example, is performed at the same timing as step S3. However, step S7 may also be performed before or after step S3. An additive manufacturing device 302 capable of performing step S7 will be described with reference to Figures 10 and 11.

Figure 10 is a structural diagram showing an additive manufacturing apparatus 302 according to the fourth embodiment. The additive manufacturing apparatus 302 is similar to the additive manufacturing apparatus 300 (Figure 2), except that it includes a modeling apparatus main body 102 instead of the modeling apparatus main body 100 (Figure 2). The modeling apparatus main body 102 is similar to the modeling apparatus main body 100 (Figure 2), except that it further includes a temperature sensor 55.

The temperature sensor 55 measures the temperature of the stage 51 and is, for example, a thermocouple. The temperature sensor 55 is installed in contact with the underside of the metal stage 51, for example.

Figure 11 is a block diagram showing an additive manufacturing apparatus 302 according to the fourth embodiment. The determination unit 21 determines whether an overheating state has occurred based on the surface temperature of the intermediate body S measured by the temperature sensor 13 and the temperature of the stage 51 measured by the temperature sensor 55. Specific determination methods will be explained later, returning to Figure 9.

In step S4 (determination step), when the difference between the surface temperature of the intermediate S and the temperature of the stage 51 falls below a predetermined threshold value indicating that the intermediate S is overheated, it is determined that the intermediate S is not overheated. As described above, the intermediate S easily dissipates heat to the stage 51. Furthermore, the stage 51 is not irradiated with the light beam L and is therefore less susceptible to the direct effects of heating from the light beam L, so its temperature remains relatively constant. Therefore, the heat of the intermediate S, which has been heated by irradiation with the light beam L, is easily transferred to the stage 51. This heat transfer reduces the difference between the surface temperature of the intermediate S and the temperature of the stage 51. Therefore, this difference is compared with the threshold value, and when the difference falls below the predetermined threshold value, it is determined that the temperature of the intermediate S has dropped and that the intermediate S is not overheated. This also makes it possible to suppress structural abnormalities caused by overheating.

Figure 12 is a flowchart showing a method for manufacturing a layered object R (Figure 4A) according to a fifth embodiment (hereinafter referred to as the manufacturing method of the fifth embodiment). The manufacturing method of the fifth embodiment is similar to the manufacturing method of the first embodiment, except that it further includes step S8 after step S3.

Step S8 (irregularity detection step) is a step in which irregularities are detected by imaging the surface of the intermediate body S while irradiating it with light. Step S8 makes it possible to detect irregularities that may exist on the surface of the intermediate body S, and the detection results can be used for control, which will be described later. An additive manufacturing device 303 capable of executing step S8 will be described with reference to Figures 13 and 14.

Figure 13 is a structural diagram showing an additive manufacturing apparatus 303 of the fifth embodiment. The additive manufacturing apparatus 303 is similar to the additive manufacturing apparatus 300 (Figure 2), except that it includes a modeling apparatus main body 103 instead of the modeling apparatus main body 100 (Figure 2). The modeling apparatus main body 103 is similar to the modeling apparatus main body 100 (Figure 2), except that it further includes an unevenness detection device 56.

The unevenness detection device 56 includes an imaging device 57 and an illumination device 58. The imaging device 57 is provided, for example, above the intermediate body S in a position where it can capture an image of the surface of the intermediate body S (for example, the upper surface of a predetermined layer, which is the metal layer 507 (Figure 4B)). The imaging device 57 is, for example, a camera. The illumination device 58 is positioned so that it has an optical axis E at an angle, for example, greater than 0° and less than 90°, relative to the surface of the intermediate body S. With this arrangement, if unevenness exists on the leaf surface of the intermediate body S, the imaging device 57 can capture the shadows caused by the unevenness and detect the unevenness.

Figure 14 is a block diagram showing an additive manufacturing apparatus 302 according to the fifth embodiment. The determination unit 21 determines whether or not the intermediate body S is in an overheated state based on the surface temperature measured by the temperature sensor 13 and the detection results of the unevenness detection device 56. Specific determination methods will be explained later, returning to Figure 12.

In step S4 (judgment step), when the surface temperature of the intermediate S falls below a predetermined threshold at the location where the irregularities detected in step S8 (irregularity detection step) occurred, it is determined that the intermediate S is not in an overheated state. The uneven portions of the intermediate S may be caused by expansion due to overheating. Therefore, by comparing the surface temperature at the location where the irregularities occurred with a predetermined threshold, it is possible to identify the location where overheating occurred, and determine that the location is not in an overheated state due to the temperature drop in that location. As a result, even if a structural abnormality actually occurs, unintended shutdowns of the additive manufacturing device 302 can be particularly effectively prevented by using the surface temperature of the structural abnormality portion as a basis.

Figure 15 is a flowchart showing a method for manufacturing a layered object R (Figure 4A) according to a sixth embodiment (hereinafter referred to as the manufacturing method of the sixth embodiment). The manufacturing method of the sixth embodiment is similar to the manufacturing method of the first embodiment, except that it further includes step S62 instead of step S6 (Figure 1). Step S62 involves waiting, as in step S6, and the recoater 70 (Figure 2) is driven during the waiting period.

Figure 16 is a diagram illustrating the operation of the recoater 70 when using the manufacturing method of the sixth embodiment. In the present disclosure, the recoater 70 is an example of a powder supply mechanism that supplies powder P from the material supply unit 40 to the modeling unit 50 by moving (sliding) in the left and right directions on the page (the x direction shown in Figure 4A; either one is sufficient). However, the powder supply mechanism is not limited to the recoater 70.

The position of the recoater 70 indicated by the two-dot chain line is the position in the initial state (including the standby position in the first embodiment). On the other hand, standby in step S62 (Fig. 15) is performed at the position of the recoater 70 indicated by the solid line in Fig. 16. That is, if an overheated state is determined in step S4 (Fig. 15), the modeling control unit 22 (Fig. 3) raises the stage 41 (Fig. 2) and then drives the recoater 70, which is positioned in the initial state, toward the modeling unit 50. As a result, the powder P in the material supply unit 40 (Fig. 2) is moved to the side of the modeling unit 50 by driving the recoater 70. Then, while the powder P is held to the side of the modeling unit 50, standby is performed until the overheated state is resolved.

Returning to Figure 15, step S62 (waiting step) is performed with the powder P to be supplied onto a predetermined layer within the modeling unit 50 held on the side of the modeling unit 50. As a result, when the powder bed PB is formed in step S5 after step S62, the powder P held on the side of the modeling unit 50 can be quickly supplied to the modeling unit 50, shortening the time required to form the powder bed PB.

Figure 17 is a flowchart showing a method for manufacturing a layered object R (Figure 4A) according to the seventh embodiment (hereinafter referred to as the manufacturing method of the seventh embodiment). The manufacturing method of the seventh embodiment is similar to the manufacturing method of the first embodiment, except that it includes step S63 instead of step S6 (Figure 1). Step S63 (standby step) is a standby step (standby step) similar to step S6, and includes steps S631 to S633.

Step S631 (drive start step) is a step in which, after determining in step S4 (determination step) that an overheat state has occurred, the drive of the recoater 70, which supplies powder P to the modeling unit 50, is started. The drive of the recoater 70 is executed by the modeling control unit 22 (Figure 2). By driving the recoater 70, the powder P in the material supply unit 40 (Figure 2) moves toward the modeling unit 50.

After the start of operation, a determination is made as to whether the overheated state has occurred, as in step S4 (step S632). If it is determined that the overheated state has not occurred, step S633 is performed. Step S633 (supply step) is a step in which the recoater 70 supplies powder P onto a predetermined layer in the modeling unit 50 after the recoater 70 has started operating and it is determined in step S632 that the overheated state has not occurred. In particular, by including steps S631 and S633, when forming the powder bed PB, the recoater 70, which has been driven in advance, can quickly supply powder P to the modeling unit 50 from a position closer to the modeling unit 50 than the initial position of the recoater 70 (Figure 16), thereby shortening the time required to form the powder bed PB.

The drive speed of the recoater 70 is determined, for example, based on the difference between the surface temperature determined in step S3 and the above-mentioned predetermined threshold. This shortens the time that the recoater 70 is stopped. Regarding the method of determining the drive speed, for example, if the difference is large, it will take a long time for the overheated state to disappear, so the drive speed is determined to be slow. On the other hand, for example, if the difference is small, it will take a short time for the overheated state to disappear, so the drive speed is determined to be fast. The relationship between the drive speed and the difference can be determined, for example, by experimentation, etc.

If this relationship is not used, and the recoater 70 reaches the side of the modeling unit 50 before the overheating state is resolved, the recoater 70 can be stopped at the side, as in the sixth embodiment.

Figure 18 is a flowchart showing a method for manufacturing a layered object according to an eighth embodiment (hereinafter referred to as the manufacturing method according to the eighth embodiment). The manufacturing method according to the eighth embodiment is the same as the manufacturing method according to the first embodiment, except that it further includes steps S64 and S65.

Step S64 (notification step) is a step in which, if an overheated state is determined in step S4 (determination step), an alarm is issued when the time during which the overheated state has continued exceeds a predetermined time. This predetermined time can be determined, for example, through experimentation. In the illustrated example, step S64 is performed in parallel with step S6.

As described above, the intermediate S has a heat transfer path to the stage 51 (Figure 2), so its temperature will decrease, although the rate of temperature decrease may differ. However, if the intermediate S is damaged during additive manufacturing, for example, the portion separated from the intermediate S due to the damage will have a slower rate of temperature decrease than the intermediate S because it does not have a heat transfer path. Therefore, the separated portion will remain in an overheated state for a longer period of time (for example, the time it exceeds a predetermined threshold) than the intermediate S. Therefore, in step S8, the notification unit 23 (Figure 19) notifies the user that such damage has occurred when the time in the overheated state exceeds a predetermined period of time. Note that step S64 ends when step S5 is started.

Figure 19 is a block diagram showing an additive manufacturing apparatus 304 according to the eighth embodiment. The additive manufacturing apparatus 304 is similar to the additive manufacturing apparatus 300 (Figure 2), except that it includes a modeling apparatus main body 104 and a control device 204 instead of the modeling apparatus main body 100 (Figure 2) and the control device 200 (Figure 2), respectively. The specific hardware configuration of the control device 204 will be described later with reference to Figure 20. The modeling apparatus main body 104 includes an alarm device 59 in addition to the configuration of the modeling apparatus main body 100. The control device 204 includes an alarm unit 23 in addition to the configuration of the control device 200.

The notification device 59 notifies the user in response to instructions from the notification unit 23. The notification device 59 includes, for example, a speaker that emits a notification sound, a display that displays a notification screen, and a light-emitting device that emits light to notify. The notification unit 23 executes step S8 (Figure 18). That is, the notification unit 23 issues a notification through the notification device 59 based on the surface temperature determined by the temperature sensor 13 and a predetermined specified time. The notification device 59 allows the user to know of damage to the intermediate product S, etc.

Figure 20 is a block diagram illustrating the hardware configuration of the control devices 200 and 204. The control devices 200 and 204 include a CPU 901, RAM 902, ROM 903, HDD 904, communication I/F 905, input/output I/F 906, and media I/F 907. The communication I/F 905 is connected to an external communication device 915. The input/output I/F 906 is connected to an input/output device 916. The media I/F 907 reads and writes data from a recording medium 917. Furthermore, the CPU 901 executes a program (also called an application, or "app" for short) loaded into RAM 902, thereby realizing the control devices 200 and 204. This program can be distributed via a communication line or recorded on a recording medium 917 such as a CD-ROM.

10 Chamber 100 Modeling apparatus main body 101 Modeling apparatus main body 102 Modeling apparatus main body 103 Modeling apparatus main body 104 Modeling apparatus main body 12 Transmission window 12g Protective glass 13 Temperature sensor 14 Pressure sensor 15 Oxygen sensor 20 Gas supply unit 200 Control device 204 Control device 21 Determination unit 22 Modeling control unit 23 Notification unit 30 Exhaust mechanism 300 Layered modeling apparatus 301 Layered modeling apparatus 302 Layered modeling apparatus 303 Layered modeling apparatus 304 Layered modeling apparatus 31 Piping 4 Step 40 Material supply unit 41 Stage 50 Modeling unit 501 Space 502 Upper edge 503 Metal layer 505 Metal layer 507 Metal layer 51 Stage 52 Cooling mechanism 53 Side wall 54 Water flow space 55 Temperature sensor 56 Irregularity detection device 57 Imaging device 58 Lighting device 59 Notification device 60 Recovery unit 70 Recoater (powder supply mechanism)
75 Moving mechanism (powder supply mechanism)
80 Beam source D Travel direction E Optical axis L Light beam P Powder PB Powder bed R Layered object S Intermediate body S1 Step (predetermined layer formation step)
S2 Step S3 Step (Surface temperature determination step)
S31 Step S4 Step (Decision Step)
S5 Step (Powder bed formation step)
S6 step (standby step)
S61 step (cooling step)
Step S62 Step S63 Step S631 (Drive start step)
S632 Step S633 Step (supply step)
Step S65 (notification step)
Step S7 (support member temperature determination step)
Step S8 (unevenness detection step)

Claims (16)

a predetermined layer forming step of forming a predetermined layer, which is a metal layer, by irradiating a powder bed of a metal material with a light beam;
a surface temperature determination step of determining a surface temperature of the intermediate object obtained through the predetermined layer formation step;
a determining step of determining whether the intermediate object is in an overheated state based on the surface temperature and a predetermined threshold value indicating an overheated state of the intermediate object;
a powder bed forming step of forming the powder bed on the predetermined layer when it is determined that the overheating state is not present as a result of the determination in the determination step ,
In the determining step, it is determined that the overheated state does not exist when the surface temperature is equal to or lower than the predetermined threshold value,
The surface temperature is at least the surface temperature of a portion where heat is likely to accumulate, which is determined in advance based on the structure of the additive manufacturing object to be manufactured.
A method for manufacturing a layered object, comprising: 2. The method for manufacturing an additively manufactured object according to claim 1, wherein the portion includes at least one of a portion of the predetermined layer in the additively manufactured object below which a space exists, or a portion whose cross-sectional area in the direction of movement of the light beam during additive manufacturing is equal to or smaller than a predetermined area. The method for manufacturing a layered object according to claim 1 , further comprising a waiting step of, when it is determined in the determining step that the intermediate object is in an overheated state, waiting until the intermediate object is no longer in an overheated state. a predetermined layer forming step of forming a predetermined layer, which is a metal layer, by irradiating a powder bed of a metal material with a light beam;
a surface temperature determination step of determining a surface temperature of the intermediate object obtained through the predetermined layer formation step;
a determining step of determining whether the intermediate object is in an overheated state based on the surface temperature and a predetermined threshold value indicating an overheated state of the intermediate object;
a powder bed forming step of forming the powder bed on the predetermined layer when it is determined that the overheating state is not present as a result of the determination in the determination step,
further comprising a waiting step of waiting until the intermediate object is no longer in an overheated state when it is determined in the determining step that the intermediate object is in an overheated state,
the waiting step is performed in a state in which the powder of the metal material to be supplied onto the predetermined layer in a storage section that stores the intermediate object is held to a side of the storage section. The waiting step
a drive start step of starting drive of a powder supply mechanism that supplies powder of the metal material to a container that contains the intermediate object after it is determined that the intermediate object is in an overheated state in the determination step;
the powder supply mechanism starts to operate, and after determining that the powder supply mechanism is not in an overheated state, the powder is supplied onto the predetermined layer in the containing section by the powder supply mechanism. The method for manufacturing a layered object according to claim 5 , wherein the drive speed of the powder supply mechanism is determined based on a difference between the determined surface temperature and the predetermined threshold value. The method for manufacturing a layered object according to claim 1 , further comprising a cooling step of lowering the surface temperature by cooling the intermediate object during at least a part of the time from the determining step to the powder bed forming step. The method for manufacturing a layered object according to claim 7 , wherein the cooling is performed by cooling at least one of a side wall of a housing section that houses the metal material and the intermediate object, and a support member that supports the intermediate object. 9. The method for manufacturing a layered object according to claim 8 , wherein the cooling is performed by providing a cooling mechanism including at least one of a water cooling device, an air cooling device, or a heat sink to at least one of the side wall and the support member. a predetermined layer forming step of forming a predetermined layer, which is a metal layer, by irradiating a powder bed of a metal material with a light beam;
a surface temperature determination step of determining a surface temperature of the intermediate object obtained through the predetermined layer formation step;
a determining step of determining whether the intermediate object is in an overheated state based on the surface temperature and a predetermined threshold value indicating an overheated state of the intermediate object;
a powder bed forming step of forming the powder bed on the predetermined layer when it is determined that the overheating state is not present as a result of the determination in the determination step,
the predetermined threshold value is different for each of the metal layers in the intermediate object. a predetermined layer forming step of forming a predetermined layer, which is a metal layer, by irradiating a powder bed of a metal material with a light beam;
a surface temperature determination step of determining a surface temperature of the intermediate object obtained through the predetermined layer formation step;
a determining step of determining whether the intermediate object is in an overheated state based on the surface temperature and a predetermined threshold value indicating an overheated state of the intermediate object;
a powder bed forming step of forming the powder bed on the predetermined layer when it is determined that the overheating state is not present as a result of the determination in the determination step,
further comprising an unevenness detection step of detecting unevenness by imaging the surface of the intermediate object while irradiating it with light,
the determining step determines that the object is not in an overheated state when the surface temperature at a location where the irregularities detected in the irregularity detection step have occurred is equal to or lower than the predetermined threshold. The method for manufacturing a layered object according to claim 1 , further comprising a notification step of issuing a notification when it is determined in the determination step that the object is in an overheated state and a time period during which the object remains in the overheated state exceeds a predetermined time period. a molding apparatus main body that forms a predetermined layer, which is a metal layer, by irradiating a powder bed of a metal material with a light beam;
a temperature sensor for determining the surface temperature of the intermediate object obtained by forming the metal layer; and
a control device;
The control device
a determination unit that determines whether the intermediate object is in an overheated state based on the surface temperature and a predetermined threshold value that indicates an overheated state of the intermediate object;
a molding control unit that controls the molding apparatus main body to form the powder bed on the predetermined layer when it is determined that the overheating state is not present as a result of the determination by the determination unit; and
Equipped with
The determination unit determines that the overheated state does not exist when the surface temperature is equal to or lower than the predetermined threshold value,
The surface temperature is at least the surface temperature of a portion where heat is likely to accumulate, which is determined in advance based on the structure of the additive manufacturing object to be manufactured.
An additive manufacturing apparatus characterized by: a molding apparatus main body that forms a predetermined layer, which is a metal layer, by irradiating a powder bed of a metal material with a light beam;
a temperature sensor for determining the surface temperature of the intermediate object obtained by forming the metal layer; and
a control device;
The control device
a determination unit that determines whether the intermediate object is in an overheated state based on the surface temperature and a predetermined threshold value that indicates an overheated state of the intermediate object;
a molding control unit that controls the molding apparatus main body to form the powder bed on the predetermined layer when it is determined that the overheating state is not present as a result of the determination by the determination unit; and
Equipped with
When the determination unit determines that the intermediate product is in an overheated state, the powder of the metal material to be supplied onto the predetermined layer in a container unit that contains the intermediate product is held on a side of the container unit and waits until the intermediate product is no longer in an overheated state.
An additive manufacturing device characterized by: a molding apparatus main body that forms a predetermined layer, which is a metal layer, by irradiating a powder bed of a metal material with a light beam;
a temperature sensor for determining the surface temperature of the intermediate object obtained by forming the metal layer; and
a control device;
The control device
a determination unit that determines whether the intermediate object is in an overheated state based on the surface temperature and a predetermined threshold value that indicates an overheated state of the intermediate object;
a molding control unit that controls the molding apparatus main body to form the powder bed on the predetermined layer when it is determined that the overheating state is not present as a result of the determination by the determination unit; and
Equipped with
The predetermined threshold value differs for each of the metal layers in the intermediate object.
An additive manufacturing device characterized by: a molding apparatus main body that forms a predetermined layer, which is a metal layer, by irradiating a powder bed of a metal material with a light beam;
a temperature sensor for determining the surface temperature of the intermediate object obtained by forming the metal layer; and
a control device;
The control device
a determination unit that determines whether the intermediate object is in an overheated state based on the surface temperature and a predetermined threshold value that indicates an overheated state of the intermediate object;
a molding control unit that controls the molding apparatus main body to form the powder bed on the predetermined layer when it is determined that the overheating state is not present as a result of the determination by the determination unit; and
an unevenness detection unit that detects unevenness by capturing an image of the surface of the intermediate object while irradiating the surface with light,
The determination unit determines that the overheating state does not exist when the surface temperature at the location where the unevenness detected by the unevenness detection unit occurs becomes equal to or lower than the predetermined threshold value.
An additive manufacturing device characterized by: