JP2023105840A - Metal laminate molding apparatus - Google Patents

Abstract

To provide a metal laminate molding apparatus that can improve the shape accuracy in a first area portion where there is no sustainment due to nonexistence of a molding portion solidified by an optical beam in a lower part in a lamination direction.SOLUTION: A metal laminate molding apparatus for laminate molding a structure by a repetition of irradiating a powder layer which is a layer of metal powder, with an optical beam and laminating it through melting and solidification, wherein the structure has a first area portion where no molding portion solidified by the optical beam exists in a lower part in a lamination direction, and a second area portion where the molding portion exists in the lower part, comprises a storage portion that previously stores identification information for identifying the first area portion and the second area portion, and a condition adjusting portion that adjusts a molding condition for determining an energy density so as to input heat with a lower energy density during molding the first area portion than during molding the second area portion based on the identification information.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a metal additive manufacturing apparatus.

Conventionally, as described in Patent Document 1, for example, there is known a metal additive manufacturing apparatus that laminates and models a structure by repeatedly irradiating a layer of metal powder with a light beam such as a laser to melt, solidify, and laminate. It is Various metals such as aluminum, titanium, nickel, stainless steel, and copper alloys are used as the metal powder. Since such a metal additive manufacturing apparatus is capable of fine modeling, it is expected to be used in various fields from mechanical parts to electrical parts.

JP 2021-167452 A

However, when a structure, such as a water pipe, in which an axially extending cavity used as a flow path is formed inside, is laminated from bottom to top in a cross section on a plane perpendicular to the axial direction, A large shape error may occur in the upper half of the structure in the direction of gravity. Specifically, in the cross section of the plane perpendicular to the axial direction of the flow channel, the lower half of the part forming the inner peripheral surface in the direction of gravity has a molded part that serves as a support during molding, so it is highly accurate. molding becomes possible. However, the upper half of the part that forms the inner peripheral surface in the direction of gravity does not have a part that has already been formed (solidified part) at the time of modeling, and there is no support. However, there is a problem that excessive heat input occurs, shape errors occur, and shape accuracy deteriorates.

The present disclosure can be implemented as the following forms.

(1) According to one aspect of the present disclosure, a metal additive manufacturing apparatus is provided. This metal additive manufacturing apparatus is a metal additive manufacturing apparatus that laminates and shapes a structure by repeatedly irradiating a powder layer, which is a layer of metal powder, with a light beam to melt, solidify, and laminate. and a first area portion in which the shaped portion solidified by the light beam does not exist at a lower portion in the lamination direction, and a second area portion in which the shaped portion exists at a lower portion, wherein the first area portion and the second area portion are provided. a storage unit for pre-storing identification information for identifying the area portion; and a storage unit configured to input heat at a lower energy density when molding the first area portion than when molding the second area portion based on the identification information. and a condition adjustment unit that adjusts a molding condition that determines the energy density.
When forming the first area where the modeled part solidified by the light beam does not exist at the bottom in the stacking direction and has no support, the light beam is emitted with the same energy density as the second area where the modeled part that serves as the support exists at the bottom. When irradiated, there is a risk of excessive heat input as compared with the second area portion, which tends to cause shape errors, and deteriorates shape accuracy. According to the metal additive manufacturing apparatus of the above aspect, the storage section stores identification information for identifying the first area section and the second area section. Then, based on the identification information, the condition adjustment unit can adjust the modeling conditions for determining the energy density so that heat input is performed at a lower energy density when modeling the first area than when modeling the second area. Therefore, excessive heat input to the first area can be suppressed, and shape accuracy can be improved.
(2) In the above aspect, the memory portion is a generating portion in which warping exceeding a predetermined shape error occurs when modeling is performed with the same energy density as that of the second area portion in the first area portion. and a non-warp portion that does not generate warpage when formed with the same energy density as the second area portion, and further stores information as the identification information, and the condition adjustment unit is configured to: So that the beam output, which is the output, is the same as the beam output during modeling of the non-generating portion, and the temperature at the time of beam irradiation in the generating portion is the same as the temperature at the time of beam irradiation in the non-generating portion, A condition different from the beam output may be adjusted as the shaping condition when shaping the generating portion.
According to the metal additive manufacturing apparatus of this aspect, in the first area part, when modeling is performed under the same modeling conditions as the second area part, the warp exceeding a predetermined shape error occurs in the generated part, The condition adjusting section can adjust the heat input at an energy density lower than that during the modeling of the second area section. The non-generating portion does not warp even if the energy density is the same as that of the second area portion, so adjustment of the energy density is not required. The above embodiment is a preferred embodiment in which adjustments are made to necessary parts in order to reduce the energy density of the warping portion where the warp occurs beyond the shape error that degrades the shape accuracy. can be done.
(3) In the above aspect, the metal powder may be a copper alloy. Copper alloy powder has a high reflectance and does not easily absorb the energy of a light beam, so lamination molding is relatively difficult. Even with such a copper alloy powder, it is possible to improve the shape accuracy of the structure formed by the metal additive manufacturing apparatus of the above embodiment.
(4) In the above aspect, the structure may have a conduit through which a fluid flows, and the first area portion may be formed in a curved inner peripheral part forming the conduit. According to the metal additive manufacturing apparatus of this aspect, it is possible to improve the shape accuracy of the first area formed in the curved inner peripheral portion of the structure having the pipeline.
(5) In the above aspect, the structure may be a coil for high-frequency heat treatment. According to the metal additive manufacturing apparatus of this embodiment, a coil for high-frequency heat treatment can be manufactured with high shape accuracy by additive manufacturing.
(6) In the above aspect, the condition adjustment unit adjusts at least one of the scanning speed of the light beam, the scanning pitch of the light beam, and the thickness of the powder layer as the molding condition. good too. According to the metal additive manufacturing apparatus of this aspect, the energy density can be adjusted using at least one of the scanning speed of the light beam, the scanning pitch of the light beam, and the lamination thickness of the powder layer.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows schematic structure of the metal lamination-molding apparatus in 1st Embodiment of this indication. FIG. 4 is a schematic diagram for explaining beam irradiation by a beam irradiation device; It is a schematic block diagram which shows the functional structure of a metal lamination-molding apparatus. It is a sectional view showing a structure modeled by a metal additive manufacturing apparatus. FIG. 4 is a schematic diagram for explaining a theoretical formula of energy density during beam irradiation; FIG. 4 is a diagram showing correspondence between energy density and temperature at the time of beam irradiation; It is a figure which shows the correspondence between energy density and modeling conditions. FIG. 8 is a cross-sectional photograph showing an enlarged part of the structure formed through the condition adjustment shown in FIG. 7. FIG. It is a figure which shows the correspondence between energy density and modeling conditions. FIG. 10 is a cross-sectional photograph showing an enlarged part of the structure formed through the condition adjustment shown in FIG. 9. FIG. FIG. 11 is a diagram for explaining the occurrence of a shape error when modeling is performed by changing the radius of the pipeline with the metal additive manufacturing apparatus of the comparative embodiment; FIG. 5 is a diagram for explaining the occurrence of a shape error when the metal additive manufacturing apparatus of the first embodiment is used to change the radius of the pipeline for modeling.

A. First embodiment:
A1. Overall configuration of metal additive manufacturing apparatus 1:
FIG. 1 is a cross-sectional view showing a schematic configuration of a metal additive manufacturing apparatus 1 according to the first embodiment of the present disclosure. The metal additive manufacturing apparatus 1 laminate-models a three-dimensional structure W by a powder bed method. Specifically, the metal additive manufacturing apparatus 1 irradiates the powder layer PL, which is a layer of the metal powder M, with a laser beam to melt and solidify, and then covers the upper layer with the metal powder M again to form the powder layer PL. , and irradiating a laser beam thereon are repeated, and the structure W is formed by stacking layers.

In the first embodiment, a laser beam is used as the light beam. In addition to the laser beam, the light beam includes an electron beam and various other beams capable of melting the metal powder M. Various lasers such as near-infrared wavelength lasers, CO2 lasers (far-infrared lasers), and semiconductor lasers can be applied to the laser beam, which are appropriately determined according to the metal powder M to be processed. Moreover, in 1st Embodiment, the metal powder M is a copper alloy. As the metal powder M, various metal materials such as aluminum, pure copper, steel materials such as maraging steel and inconel, and stainless steel can be applied in addition to copper alloys.

The metal additive manufacturing apparatus 1 includes a chamber 10, a model support device 20, a powder supply device 30, and a beam irradiation device 40, as shown in FIG. The chamber 10 is configured such that the internal air can be replaced with an inert gas such as He (helium), N2 (nitrogen) or Ar (argon). In addition, the chamber 10 may be configured to be depressurized instead of replacing the inside with an inert gas.

The modeled object support device 20 is provided inside the chamber 10 and is a part for modeling the structure W. As shown in FIG. The modeled object support device 20 includes a modeling container 21 , an elevating table 22 , and a base 23 . The modeling container 21 has an opening on the upper side and an inner wall surface parallel to the vertical axis. The elevating table 22 is provided so as to be vertically movable inside the molding container 21 along the inner wall surface. The base 23 is detachably attached to the upper surface of the elevating table 22, and the upper surface of the base 23 serves as a part for forming the structure W. As shown in FIG. In other words, the base 23 has the metal powder M layered on its upper surface and supports the structure W during molding. By changing the positioning height of the lifting table 22, the layer thickness of the metal powder M can be changed.

The powder supply device 30 is provided inside the chamber 10 and adjacent to the model support device 20 . The powder supply device 30 includes a powder storage container 31 , a supply table 32 and a recoater 33 . The powder storage container 31 has an opening on the upper side, and the height of the opening of the powder storage container 31 is the same as the height of the opening of the modeling container 21 . The powder storage container 31 has an inner wall surface parallel to the vertical axis. The supply table 32 is provided so as to be vertically movable inside the powder storage container 31 along the inner wall surface. In the powder storage container 31 , the metal powder M is stored in the upper area of the supply table 32 .

The recoater 33 is provided so as to be able to reciprocate along the upper surfaces of both openings over the entire area of the opening of the modeling container 21 and the opening of the powder storage container 31 . The recoater 33 conveys the metal powder M protruding from the opening of the powder storage container 31 to the molding container 21 side when moving from right to left in FIG. Further, the recoater 33 arranges the conveyed metal powder M in a layer on the upper surface of the base 23 . In addition to the above configuration, the movable recoater 33 itself may have the function of supplying the metal powder M. In this case, the metal powder M is flattened while being fed onto the base 23 by the recoater 33 .

FIG. 2 is a schematic diagram for explaining beam irradiation by the beam irradiation device 40. As shown in FIG. As shown in FIG. 2, the beam irradiation device 40 irradiates a beam onto the surface of the powder layer PL, which is a layer of metal powder M arranged on the upper surface of the base 23 . The beam irradiation device 40 heats the metal powder M to a temperature equal to or higher than the melting point of the metal powder M by irradiating the metal powder M arranged in layers with a beam. Then, the metal powder M is melted and then solidified to form integrated layered shaped parts W11, W12, and W13 (all of which are part of the structure W). That is, adjacent metal powders M are integrated by fusion bonding.

FIG. 3 is a schematic block diagram showing the functional configuration of the metal additive manufacturing apparatus 1. As shown in FIG. As shown in FIG. 3 , the metal additive manufacturing apparatus 1 includes a control device 50 . The control device 50 includes a storage section 51 and a condition adjustment section 52 . The storage unit 51 stores various information about the structure W. FIG. Specifically, for example, on the basis of the three-dimensional data of the structure W, the slicer software or the like is used to store information on the two-dimensional cross-sectional shape of the laminated structures.

The control device 50 is, for example, a microcomputer including a CPU, a ROM, a RAM, other input/output ports, etc., and controls the metal additive manufacturing apparatus 11 as a whole. The CPU of such a microcomputer functions as the condition adjusting section 52 by reading and executing the program stored in the ROM.

FIG. 4 is a cross-sectional view showing a structure W1 that is modeled by the metal additive manufacturing apparatus 1. As shown in FIG. A structure W1 to be formed in the first embodiment is a coil for high-frequency heat treatment. The structure W1 has a pipeline 60 through which water as a fluid flows. FIG. 4 shows a cross section taken along a plane perpendicular to the axial direction in which the pipeline 60 extends (hereinafter simply referred to as an "axial cross section"). The right side of FIG. 4 is an enlarged view of the periphery of the pipeline 60 on the left side of FIG. The axial cross-sectional shape of the conduit 60 is substantially semicircular. The radius R of the conduit 60 is 8 mm. The axial cross-sectional shape of the pipeline 60 is not limited to a substantially semicircular shape, and may be a perfect circle, an ellipse, a polygon such as a triangle or a quadrangle, or a shape formed by arbitrary straight lines and curves.

The structure W1 has a first area portion 61 and a second area portion 62 . The first area portion 61 is a portion of the structure W1 in which the shaped portion solidified by the light beam does not exist in the lower portion in the stacking direction Z. As shown in FIG. Specifically, the first area portion 61 is formed outside the pipeline 60 and on the curved inner peripheral portion. The second area portion 62 is a portion of the structure W1 below which the shaped portion solidified by the light beam exists. Specifically, the second area portion 62 is a portion located outside the straight line portion and the inner peripheral portion that is the outer lower portion of the pipe 60 and the inner peripheral portion, and the shaped portion is the lower portion in the stacking direction Z It is formed in a part that does not exist in the

Note that FIG. 4 shows the shape when the energy density E, which will be described later, is not adjusted in the condition adjustment unit 52, and the first area portion 61 and the second area portion 62 are all formed under the same forming conditions. ing. Therefore, the shape collapse is seen in the vicinity of the top surface portion 66 shown by enclosing it with a dashed line. It should be noted that ``when the energy density E is not adjusted in the condition adjustment unit 52 and all the first area parts 61 and the second area parts 62 are molded under the same molding conditions'' will be hereinafter simply referred to as ``condition When no adjustment is made”.

The first area portion 61 formed without condition adjustment is divided into a generated portion 64 and a non-generated portion 65 . The generating portion 64 is a portion where warping exceeding a predetermined permissible shape error occurs when the beam is irradiated under the same molding conditions as the second area portion 62 to shape. The non-warping part 65 is a part where the warp does not occur when the beam is irradiated under the same shaping conditions as the second area part 62 to form the part. "Warping exceeding the allowable shape error" is, for example, warping exceeding the thickness of one layer. As shown enlarged on the right side in FIG. 4, of the first area portion 61, for example, the 379th layer is a layer having the non-generating portion 65, and the 399th layer is a layer partially having the generating portion 64. As shown in FIG.

The storage section 51 stores identification information for identifying the first area section 61 and the second area section 62 . Furthermore, the storage unit 51 stores information for identifying the generating unit 64 and the non-generating unit 65 as identification information.

The condition adjustment unit 52 adjusts modeling conditions including various irradiation conditions and lamination thickness of the beam irradiation device 40 based on the identification information. Specifically, the condition adjustment unit 52 adjusts the heat input at the energy density E lower than that of the non-generating portion 65 and the second area portion 62 when forming the generating portion 64 . A detailed description of the condition adjustment using specific numerical data will be given later.

FIG. 5 is a schematic diagram for explaining the theoretical formula of the energy density E during beam irradiation. The condition adjustment unit 52 changes the irradiation position, laser output P [W], scanning speed v [mm/s], scanning pitch s [mm], lamination thickness t [mm], etc., according to a preset program. A desired layered object can be formed by changing the irradiation position. Further, by changing the laser output P, the amount of heat input into the metal powder M is changed, and the bonding strength between the metal powders M can be changed. The energy density E, which correlates with the amount of heat input, can be adjusted by parameters based on the following theoretical formula (1).
Energy density: E=P/(v×s×t) (1)

A2. Adjustment by condition adjustment unit 52:
Next, the condition adjustment performed by the condition adjusting unit 52 when the structure W1 is formed by the metal additive manufacturing apparatus 1 will be described using data. The condition adjusting unit 52 adjusts the beam output when forming the generating unit 64 to be the same as the beam output when forming the non-generating unit 65, and sets the beam output temperature of the generating unit 64 at the time of beam irradiation to the non-generating unit 65. The shaping conditions different from the beam power are adjusted so as to be the same as the temperature.

It should be noted that the terms "same" and "same" as used herein are not limited to "same" and "same" in the strict sense, but usually "same" and "same" in light of common technical knowledge in the relevant technical field. "Identical" and "same" are construed to the extent that they have identity to the extent that they are determined to be. Specifically, a difference due to an increase or decrease of about 20% from the reference value may be included in the same item.

FIG. 6 is a diagram showing the correspondence between the energy density E and the temperature at the time of beam irradiation. Here, the "beam irradiation temperature" is the average temperature around the laser irradiation point. The vicinity of the laser irradiation point includes a molten pool N (see FIG. 5) formed by melting the metal powder M by laser irradiation. In the data shown in FIG. 6, the "temperature during irradiation" is derived by plotting a plurality of points around the laser irradiation point and analyzing them.

The aspect of the structure when formed with the energy density E shown in case 1 and case 2 in FIG. 6 matches the structure W1 shown in FIG. As shown in cases 1 and 2 of FIGS. 4 and 6, when the energy density E is 231 J/mm ³ , no warpage occurs in layer 379, and warpage occurs in the vicinity of the top surface 66 in layer 399 in layer 399. It occurred, and the model collapse occurred. Comparing the temperatures during irradiation obtained by the above analysis, the temperature during irradiation of the generating portion 64 in the 399th layer was 3700°C, and the temperature during irradiation of the non-generating portion 65 in the 379th layer was 1350°C.

That is, the non-generating portion 65 (layer 379) had a significantly higher temperature during irradiation. As shown in FIG. 4, the inventors of the present application have studied and found that even in the first area portion 61 having no lower support, the portion closer to the top surface portion 66 loses its shape. Specifically, the portion near the top surface portion 66 has a tangent angle θ of the inner peripheral surface (the angle between the tangent line and the horizontal plane passing through the contact point, which is the counterclockwise angle in FIG. 4) of 30 degrees to 150 degrees. It is a part of the area of The portion where the tangential angle θ is around 90 degrees had the largest shape error.

Here, the principle of occurrence of shape collapse will be briefly described. The length L1 (see FIG. 2) of the portion of the powder layer PL to be irradiated with the laser increases as the molding progresses and the layers are stacked from the lower portion to the vicinity of the top surface portion 66 . In particular, in the powder layer PL near the top surface portion 66, when the metal powder M is irradiated with the laser, the length L2 of the portion where the metal powder M is not solidified immediately below the irradiated portion is greater than the corresponding length L3 of the lower layer. too long. That is, the contact area with the portion where the metal powder M is not solidified is increased. The non-solidified metal powder M has a lower thermal conductivity than the solidified metal, and the thickness of one powder layer PL is as thin as 40 μm. If the energy density E is the same as the laser irradiation to 65, it is difficult to dissipate the heat to the layer below and the heat is accumulated.

As a result, the amount of heat input to the generating section 64 increases, that is, the thermal expansion becomes larger than that of the lower layer (for example, when forming the forming section W13, the forming section W12, which is one lower layer shown in FIG. 2), and eventually When the generating portion 64 was cooled and contracted, the lower layer side was warped upward because the shape was retained. When the warp occurs, when the metal powder M is spread over the upper portion by the recoater 33, it cannot be spread evenly. Alternatively, even if it is laid flat, the thickness of one layer is partially reduced, and furthermore, the state of excessive heat input occurs, so errors accumulate, and finally, the vicinity of the top surface portion 66 falls outside the allowable range. It was beyond and collapsed to the bottom. As a result, the shape collapsed beyond the permissible range.

Therefore, the inventor of the present application believes that if the temperature of the generating portion 64 during irradiation is lowered to the same level as the temperature of the non-generating portion 65 during irradiation, excessive heat input can be suppressed and warping can be suppressed. I thought. Again, refer to FIG. According to the analysis of the inventor of the present application, when the energy density E of the generation part 64 (399 layers) is reduced from 231 J/mm ³ shown in case 2 to 85 J/mm ³ shown in case 3, the temperature can be lowered to 1400° C., which is equivalent to the temperature of the 379 layers. We were able to. Here, the energy density E is obtained by the above formula (1). From equation (1), in order to lower the energy density E, it is conceivable to lower the laser output P, or to increase the value of any one of the scanning speed v, scanning pitch s, and lamination thickness t.

In the following, it was examined which modeling condition is suitable for lowering the energy density E. FIG. 7 is a diagram showing the correspondence between the energy density E and the molding conditions. Data obtained when the scanning speed v is used as a condition to be adjusted and the energy density E is decreased by increasing the scanning speed v. is shown. In the example shown in FIG. 7, the scanning speed v is changed from 500 mm/s to 1100 mm/s. The laser output P is reduced from 370 W to 300 W, but this is because the experiment was conducted based on the map created with the conditions of the laser output P and the scanning speed v, and was intentionally lowered. not a thing Further, in this embodiment, the second area portion 62 and the non-generation portion 65 are set to the same molding condition.

FIG. 8 is a cross-sectional photograph showing an enlarged part of the structure W2 formed through the condition adjustment shown in FIG. FIG. 9 is a diagram showing the correspondence between the energy density E and the molding conditions. Data obtained when the laser output P is used as a condition to be adjusted and the energy density E is decreased by decreasing the laser output P. is shown. In the example shown in FIG. 9, the laser output P is changed from 370W to 136W. FIG. 10 is a cross-sectional photograph showing an enlarged part of the structure W3 formed through the condition adjustment shown in FIG.

The structures W1, W2, and W3 are all modeled on water pipes of the same shape, and the finished shapes are different because they were formed under different conditions during the modeling by the metal additive manufacturing apparatus 1. ing.

As shown in FIG. 8, when the scanning speed v was adjusted to increase and the shape was modeled, the top surface portion 66 hardly collapsed, and the shape error could be reduced to 0.5 mm or less. On the other hand, as shown in FIG. 10, when the laser output P was adjusted to be small and the molding was performed, the shape error was improved to some extent, but a plurality of holes 67 were generated due to the decrease in the relative density. , a decrease in quality was observed. If a plurality of holes 67 are generated, there arises a problem that when the product is used, the structure W3 tends to crack due to mechanical stress when water pressure acts on the inner peripheral portion of the structure W3.

As described above, in order to appropriately melt the metal powder M in order to ensure the quality that does not cause the voids 67, the laser output P needs to be of a certain magnitude. In this case, it is preferable to use conditions other than the laser output P for adjustment. Specifically, it can be adjusted by increasing the value of any one of the scanning speed v, the scanning pitch s, and the layer thickness t as the modeling condition in the generator 64 .

(1) In the metal additive manufacturing apparatus 1 of the first embodiment, when forming the generating portion 64 of the first area portion 61 that does not exist directly below the forming portions W11, W12, and W13 and has no support, the non-generating portion 65 The energy density E is adjusted to be smaller by increasing the scanning speed v so that the laser output P is the same as the laser output P at the time of modeling and the temperature at the time of irradiation of the non-generating portion 65 is approximately the same. As a result, it is possible to suppress the occurrence of warpage in the layer that causes the shape collapse in the first area portion 61, and improve the shape accuracy.

(2) In adjusting to reduce the energy density E, the size of the laser output P can be maintained without reducing it, so it is possible to ensure quality to the extent that the voids 67 are not generated in the finished structure W2. .

(3) FIG. 11 is a diagram for explaining the occurrence of a shape error when modeling is performed by changing the radius R of the pipeline 60 with the metal additive manufacturing apparatus 1 of the comparative form that does not have the condition adjustment unit 52. is. 12A and 12B are diagrams for explaining the occurrence of shape errors when the metal additive manufacturing apparatus 1 according to the first embodiment is used to form a structure while changing the radius R of the pipeline 60. FIG. As shown in FIG. 11, when irradiation is performed under the same conditions in the first area portion 61 and the second area portion 62 without the condition adjusting portion 52, the shape error can be suppressed to 0.5 mm or less. had a radius R of 2 mm or less. On the other hand, as shown in FIG. 12, in the modeling by the metal additive manufacturing apparatus 1 of the first embodiment, the shape error was suppressed to 0.5 mm or less in the range of the radius R up to 8 mm.

In other words, even a tubular member having a large radius R of about 8 mm can be shaped while maintaining shape accuracy. In this way, since the number of water pipe shapes that can be modeled by the metal additive manufacturing apparatus 1 increases, compared to the case of manufacturing by other methods such as forging and welding including manual work, the manufacturing time of the structure W2 can be shortened, It is possible to obtain the effect of improving the service life, thereby reducing the manufacturing cost.

(4) A copper alloy is used as the metal powder M in the metal additive manufacturing apparatus 1 of the first embodiment. Since the copper alloy powder has a high reflectance, it does not easily absorb the energy of the laser light, and the temperature of the powder does not rise easily. In addition, even if the temperature of the powder rises and exceeds the melting point, the thermal conductivity of the powder is about twice that of aluminum and 20 times that of stainless steel. Therefore, the time during which the powder flows beyond the melting point during laser irradiation is very short, making it difficult to obtain a high-density laminated metal. That is, copper alloys are susceptible to excessive heat input during laser irradiation, but according to the first embodiment, even with copper alloys, as described above, molding with good quality and accuracy is possible.

B. Other embodiments:
(B1) In the metal additive manufacturing apparatus 1 of the first embodiment, after distinguishing between the generated portion 64 and the non-generated portion 65 in the same layer, the scanning speed v is greatly changed for the generated portion 64. However, the scanning speed v may be adjusted for each layer. For example, in the above example, the energy density E may be adjusted to be smaller for the entire 399 layers including the generating portion 64 .

Although the layer thickness t cannot be adjusted to be different in one layer, the thickness of one layer as a whole can be adjusted by adjusting the amount of descent of the elevation table 22 of the object support device 20. . The scanning speed v and the scanning pitch s may be adjusted for each layer in the same manner as described above, or may be adjusted only for the generator 64 according to the scanning portion in one layer.

(B2) In the metal additive manufacturing apparatus 1 of the first embodiment, the structure W was described as an example of a water pipe that is a coil for high-frequency heat treatment, but the structure W is not limited to such a water pipe. If the structure W has a first area portion 61 in which the solidified shaped portion does not exist at the bottom in the stacking direction Z and a second area portion 62 in which the shaped portion exists at the bottom, the metal additive manufacturing apparatus according to the present disclosure 1 is applicable.

(B3) In the metal additive manufacturing apparatus 1 of the first embodiment, the scanning speed v is adjusted to be increased when forming the generating portion 64, but the entire first area portion 61 including the non-generating portion 65 is In modeling, adjustment may be made to input heat at an energy density E lower than that of the second area portion 62 .

(B4) In the metal additive manufacturing apparatus 1 of the first embodiment, adjustment was made by increasing the scanning speed v in order to reduce the energy density E, but increasing parameters such as the scanning pitch s and the layer thickness t may be adjusted by Also, a plurality of these parameters may be combined for adjustment.

(B5) In the metal additive manufacturing apparatus 1 of the first embodiment, the identification information for identifying the generating portion 64 is identified based on the data of actual warpage in a preliminary test. In addition, estimation based on the relationship between the radius and tangential angle of the pipe that is expected to warp from the data accumulated during modeling, and the length of the area directly below the irradiated area where the metal powder M has not solidified. may be used to identify the generator.

The present disclosure is not limited to the above embodiments, and can be implemented in various configurations without departing from the scope of the present disclosure. For example, the technical features in each embodiment corresponding to the technical features in each form described in the outline of the invention are used to solve some or all of the above problems, or In order to achieve some or all of them, it is possible to appropriately replace or combine them. Also, if the technical features are not described as essential in this specification, they can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 1... Metal additive manufacturing apparatus, 10... Chamber, 11... Metal additive manufacturing apparatus, 20... Molded object support apparatus, 21... Modeling container, 22... Lifting table, 23... Base, 30... Powder supply apparatus, 31... Powder storage Container 32 Supply table 33 Recoater 40 Beam irradiation device 50 Control device 51 Storage unit 52 Condition adjustment unit 60 Pipe line 61 First area unit 62 Second area Part 64 Generated part 65 Non-generated part 66 Top surface part 67 Void W, W1, W2, W3 Structure W11, W12, W13 Shaped part

Claims (6)

A metal additive manufacturing apparatus for additively manufacturing a structure by repeatedly irradiating a powder layer, which is a layer of metal powder, with a light beam to melt, solidify, and laminate,
The structure has a first area portion where the shaped portion solidified by the light beam does not exist below in the stacking direction, and a second area portion where the shaped portion exists below,
a storage unit that stores in advance identification information that identifies the first area portion and the second area portion;
A condition adjustment unit that adjusts a molding condition that determines the energy density based on the identification information so that heat is input at a lower energy density when molding the first area than when molding the second area. and,
A metal additive manufacturing apparatus comprising: The storage unit
A generation portion of the first area portion that causes warpage exceeding a predetermined shape error when formed with the same energy density as that of the second area portion, and the same energy density as that of the second area portion. further storing as the identification information information identifying the non-warping portion in which the warp does not occur when shaped by
The condition adjustment unit
The beam output, which is the output of the light beam, is the same as the beam output during molding of the non-generating portion, and the temperature at the time of beam irradiation in the generating portion is the same as the temperature at the time of beam irradiation in the non-generating portion. so that
Adjusting a condition different from the beam output as the shaping condition when shaping the generating part;
The metal additive manufacturing apparatus according to claim 1. 3. The metal additive manufacturing apparatus according to claim 1, wherein the metal powder is a copper alloy. The structure has a conduit through which a fluid flows,
The metal additive manufacturing apparatus according to any one of claims 1 to 3, wherein the first area portion is formed in a curved inner peripheral portion forming the pipeline. 5. The metal additive manufacturing apparatus according to claim 4, wherein the structure is a coil for high-frequency heat treatment. The condition adjustment unit
According to any one of claims 1 to 5, wherein at least one of the scanning speed of the light beam, the scanning pitch of the light beam, and the lamination thickness of the powder layer is adjusted as the molding condition. A metal additive manufacturing apparatus as described.

Images