Additive manufacturing apparatus and method for manufacturing additive manufactured article

Abstract

To provide a DED-type additive manufacturing apparatus capable of realizing a wide cooling rate and of manufacturing an additive manufactured article having desired characteristics, and to provide a method for manufacturing an additive manufactured article.MEANS FOR SOLVING THE PROBLEM: A method for manufacturing an additive manufactured article includes: a powder material-supplying step of supplying a powder material toward a base plate on a rotary table; a melting step of irradiating the powder material supplied toward the base plate with a light beam and melting the powder material; and a solidifying step of adhering the melted powder material to the base plate, air-cooling the melted powder material, and then solidifying the melted powder material to form a bead on the base plate. The powder material-supplying step, the melting step, and the solidifying step are performed while rotating the rotary table in a direction perpendicular to an irradiation direction of the light beam, and the additive manufactured article is formed by repeating these steps.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an additive manufacturing device and a method for manufacturing an additively manufactured product. [Background technology]

[0002] In recent years, additive manufacturing (also known as layered manufacturing) has come into use as a method for producing metal components. One additive manufacturing method, Directed Energy Deposition (DED), uses focused thermal energy to melt, bond, and deposit materials. Compared to other additive manufacturing methods, DED is characterized by its shorter manufacturing time and ability to produce large items.

[0003] Patent Document 1 discloses a DED manufacturing method in which a laser is irradiated onto a mixed powder to melt and bond the powder together and the base, and then the powder is cooled at a rate of approximately 10,000 K / s to form an iron-based alloy on the base. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-032589 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional DED additive manufacturing methods such as that described in Patent Document 1, the laser is irradiated at one point for a long period of time, which causes heat to be input to the powder material and the device structure arranged around the molten powder material, resulting in a problem that the cooling of the molten powder material is slower than other additive manufacturing methods. As a result, conventional DED additive manufacturing methods do not provide a sufficient cooling rate, and in some cases, the alloy structure formed by other additive manufacturing methods is not formed, making it impossible to obtain an additive product with the desired properties.

[0006] The present invention has been made in consideration of these circumstances, and provides a DED type additive manufacturing device and a method for manufacturing additive products that can improve the cooling rate of molten powder material by reducing the heat input not only to the molten powder material but also to its surroundings, thereby producing additive products with desired properties. [Means for solving the problem]

[0007] The first aspect of the present invention is a method for manufacturing an additive product, which comprises a powder material supplying step of supplying powder material toward a base plate on a rotary table, a melting step of irradiating a light beam onto the powder material supplied toward the base plate to melt the powder material, and a solidification step of adhering the molten powder material to the base plate, air-cooling it, and solidifying it to form a bead on the base plate, and is characterized in that the powder material supplying step, the melting step, and the solidification step are performed while rotating the rotary table in a direction perpendicular to the irradiation direction of the light beam, and these steps are repeated to form an additive product.

[0008] It is also preferable that the light beam is irradiated and the powder material is supplied to a position that is 200 mm or more away from the center of rotation of the rotary table, and that the rotary table controls the rotation of the base plate so that the rotation speed is 800 rpm or more and 2000 rpm or less.

[0009] It is also preferable that the light beam is a laser beam, the output of the laser beam is 2 kW or more and 6 kW or less, and the beam diameter φ of the laser beam on the base plate is 1 mm or more and 3 mm or less.

[0010] It is also preferable that the light beam is a laser beam, the output of the laser beam is 3 kW or more and 6 kW or less, and the beam diameter φ of the laser beam on the base plate is 1 mm or more and 3 mm or less.

[0011] The base plate is also characterized in that the molten powder material adhering to the base plate is air-cooled by rotating.

[0012] The powder material is preferably a Ni-based alloy powder.

[0013] The additive manufacturing device of the second present invention comprises a light beam irradiation head unit that irradiates a light beam and supplies powder material, a base plate installed in the direction of light beam irradiation from the light beam irradiation head unit, a turntable installed below the base plate and rotating the base plate in a direction perpendicular to the light beam irradiation direction, and a base unit installed below the turntable and moving the turntable in a direction perpendicular to the light beam irradiation direction, and is characterized in that the light beam and powder material are simultaneously irradiated and supplied from the light beam irradiation head unit toward the base plate while the turntable is rotating.

[0014] Furthermore, it is preferable that the base portion controls the light beam irradiation position on the base plate so that the distance from the rotation center of the rotary table on the base plate to the light beam irradiation position is 200 mm or more, and that the rotary table controls the rotation of the base plate so that the rotation speed is 800 rpm or more and 2000 rpm or less.

[0015] It is also preferable that the light beam is a laser beam, the output of the laser beam is 2 kW or more and 6 kW or less, and the beam diameter φ of the laser beam on the base plate is 1 mm or more and 3 mm or less.

[0016] It is also preferable that the light beam is a laser beam, the output of the laser beam is 3 kW or more and 6 kW or less, and the beam diameter φ of the laser beam on the base plate is 1 mm or more and 3 mm or less. [Effects of the Invention]

[0017] According to the additive manufacturing device disclosed herein, it is possible to provide a DED type additive manufacturing device and a method for manufacturing additive products that can improve the cooling rate of the molten powder material by reducing the heat input generated not only in the molten powder material but also in its surroundings, thereby producing additive products with desired properties. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram showing the basic configuration of an additive manufacturing apparatus 100 according to an embodiment of the present invention. [Figure 2] (a) A cross-sectional structure image of a bead produced under each molding condition in an example of the present invention. [Figure 3] FIG. 10 is a diagram showing whether or not a bead can be formed when the scanning speed is kept constant and other conditions are changed in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the accompanying drawings. First, an additive manufacturing apparatus of the present invention will be described, and then a manufacturing method of an additive product using the additive manufacturing apparatus of the present invention will be described.

[0020] [About additive manufacturing equipment] 1 shows the basic configuration of an additive manufacturing apparatus 100 of the present invention. The additive manufacturing apparatus 100 is mainly equipped with a light beam irradiation head unit (hereinafter simply referred to as the head unit) 110 connected to a powder material supply device inside a chamber, a base unit 120, and a rotary table 130. With this configuration, powder material is supplied toward a base plate 131 on the rotating rotary table 130, while the powder material is melted and solidified by the light beam to form a solidified layer 140. By repeating this process, an additive product can be manufactured, and rapid cooling of the molten powder material and rapid modeling of additive products can be achieved.

[0021] The chamber is preferably provided for performing additive manufacturing by replacing the air with an inert gas. Some powder materials used in additive manufacturing have highly reactive compositions, and replacing the air with an inert gas is necessary to prevent these materials from reacting with air and oxidizing. While the inert gas used is not particularly limited, argon (Ar) or nitrogen (N2) are preferred for cost and availability. To replace the atmosphere with an inert gas, the chamber is isolated from the outside and has an inert gas supply and exhaust section. For safety reasons, the chamber is preferably explosion-proof. The cooling medium for the melted powder material adhered to the base plate is not limited to air. For example, an inert gas can be used. For example, when performing additive manufacturing by replacing the chamber with an inert gas, an inert gas can be used as the cooling medium.

[0022] When replacing air with an inert gas, it is preferable to use a method in which the inert gas is sent into the chamber, and the inert gas that returns from the chamber is reacted with hydrogen to remove oxygen, and then the inert gas is circulated. The advantage of this method is that it does not require a step of evacuating the chamber once, and therefore the pressure inside the chamber does not change suddenly.

[0023] The head unit 110 is provided to irradiate the powder material on the base plate 131 with a light beam, and also to supply the powder material delivered from the powder supply device onto or above the base plate 131. An advantage of irradiating and supplying the light beam and powder material from the same head is that, as will be described later, it is easy to focus the light beam on the position where the powder material supplied from the multiple powder discharge ports in the head unit 110 converges. In addition, the head unit 110 is movable along the light beam irradiation direction. This is to keep the light beam output constant and adjust the powder material supply position according to the layer thickness of the powder material and the height of the additive product.

[0024] The head unit 110 is provided with a light beam irradiation mechanism and a light beam irradiation port, and the light beam emitted from the head unit 110 is irradiated from the head unit 110 to the base plate 131. The type of light beam is not particularly limited, but laser light is preferred due to its high resolution during modeling. Other options include electron beams and arc discharge. The output of the light beam 131 is preferably 2 kW or more and 6 kW or less, more preferably 3 kW or more and 6 kW or less, even more preferably 4 kW or more and 6 kW or less, and even more preferably more than 5 kW and 6 kW or less. The beam diameter φ on the base plate 131 is preferably 1 mm or more and 3 mm or less, more preferably 1 mm or more and 2 mm or less. By setting this output and beam diameter, sufficient energy density can be obtained to melt the powder material 110, thereby suppressing defects in the additive manufacturing product.

[0025] The head unit 110 is provided with a powder material discharge port, and preferably multiple discharge ports are provided on a concentric circle centered on the light beam irradiation port. In order to form an additive product on the base plate 131 rotating at high speed, it is necessary to irradiate the powder material discharged from the powder material discharge port toward the base plate 131 with a light beam in the air and drip the molten powder material toward the base plate 131. To achieve this, the light beam irradiation port and the powder material discharge port must be provided separately. In this case, as shown in FIG. 1, by providing multiple discharge ports on a concentric circle centered on the light beam irradiation port, the powder material discharged from the multiple discharge ports merges at a point on the irradiation path of the light beam, melts, and drips toward the base plate 131.

[0026] The powder material supply device is provided to supply powder material to the base plate 131. The powder material supply device itself may be located outside the chamber, and a supply pipe for transporting the powder material from the powder material supply device to the head unit 110 may be connected to the head unit 110.

[0027] While the method for supplying and controlling the powder material is not particularly limited, a disk-type system is preferred from the viewpoint of stabilizing the supply of the powder material. The disk-type system involves dropping the powder material into a groove on a rotating disk located below a container containing the powder, and then pressurizing the powder material into a supply pipe using a pressurized gas. This system allows the amount of powder material supplied to be easily varied and stabilized by controlling the rotation speed of the rotating disk and the pressure of the pressurized gas. When using a disk-type system, the rotation speed of the disk and the pressure of the pressurized gas are not particularly limited. The type of pressurized gas is also not particularly limited, but considering that the chamber is replaced with an inert gas as described above, it is preferable to use an inert gas as the pressurized gas. Furthermore, the number of containers containing the powder material is not limited, and can be set according to the number of types of powder to be mixed.

[0028] If the supply rate of the material powder (also simply referred to as the powder supply rate) is low relative to the energy density, the material powder may be blown up when irradiated with a light beam. For example, a range of 30 to 200 g / min is preferable, and a range of 40 to 150 g / min is more preferable.

[0029] The particle size of the powder material is not particularly limited, but it is preferable to use powder having a particle size in the range of 5 μm to 200 μm, and more preferably in the range of 10 μm to 150 μm.

[0030] The material powder may be an atomized powder produced by various atomization methods such as gas atomization, water atomization, or jet atomization, or may be a granulated powder produced using primary particle powders such as pure metal powders or alloy powders, or may be a pulverized powder obtained by pulverizing an alloy obtained by melting the alloy to obtain a desired composition.

[0031] It is also preferable to have a powder material mixing space between the powder material supply device and the head unit 110. By mixing the powder material in the mixing space before supplying the powder material from the head unit 110 to the base plate 131, it is possible to suppress bias in the composition of the additive product.

[0032] The base 120 is provided to control the irradiation position of the light beam on the base plate 131 by moving the base plate 131 on the turntable 130 placed on the base 120 in a direction perpendicular to the irradiation direction of the light beam. Being able to move the base plate 131 increases the degree of freedom in the shape of the additive product, as described below. The movement direction may be one-way or two or more directions. The method and drive direction of the base 120 are not particularly limited, but movement by rail or belt can be used. Controlling the position of the base plate 131 relative to the head 110 not only increases the degree of freedom in the shape of the additive product, but also allows for the additive manufacturing position, i.e., the irradiation position of the light beam on the base plate 131, to be changed, thereby avoiding excessive heat input to the base plate 131 and preventing a decrease in the cooling rate. The cooling rate here refers to the gradient calculated by dividing the cooling temperature by the time it takes for the molten powder material to cool to the solidification temperature.

[0033] Furthermore, it is preferable that the base unit 120 controls the position of the turntable 130 relative to the head unit 110 so that the distance from the center of rotation of the turntable 130 on the base plate 131 to the light beam irradiation position on the base plate 131 is 200 mm or more. In this specification, the effective radius refers to an area on the base plate 131 that is 200 mm or more away from the center of rotation of the turntable 130 on the base plate 131. There is also no particular upper limit to the effective radius, but it can be set to 300 mm or less in relation to the scale of the additive manufacturing apparatus 100, etc.

[0034] Furthermore, the base 120 is preferably equipped with an induction heating device, which is provided for preheating the turntable 130 and the base plate 131. Preheating the base plate 131 can prevent the molten powder material dropped onto the base plate 131 from cracking when it cools.

[0035] The turntable 130 is provided in the DED additive manufacturing device to achieve high-speed cooling of the molten metal powder. By performing additive manufacturing while rotating the turntable 130, the base plate 131 provided on the upper surface of the turntable 130 rotates together, so that the light beam passes over the molten powder material, solidified layer 140, and base plate 131 at high speed, and the heat input depth into the solidified layer and base plate 131 can be adjusted to be shallow. This improves the cooling rate of the molten powder material. The turntable 130 is provided so as to rotate perpendicular to the direction of light beam irradiation, and the base plate 131 is provided on the upper surface of the turntable 130 so as to be parallel to the direction perpendicular to the light beam irradiation direction. At this time, in order to solidify the molten powder material 110, the cooling rate must be 10 2 K / s or more 10 8 The cooling rate is preferably less than 10 K / s. 6 K / s or more 10 8 K / s, and more preferably less than 10 7 K / s or more 10 8 K / s. 6 To improve the scanning speed to 1,000,000 mm / min or more, it is preferable that the scanning speed of the light beam is 1,000,000 mm / min or more. The scanning speed here refers to the moving speed of the light beam on the base plate 131, and is calculated from Equation 1 using the effective radius and the rotation speed of the base plate 131 controlled by the rotary table 130.

[0036] [Effective radius of base plate 131] × [Rotational speed of base plate 131] × 2π (Equation 1)

[0037] The shape of the base plate 131 is not particularly limited, and examples thereof include a circular or polygonal shape when viewed from directly above the rotary table. 6If it is desired to improve the cooling rate to 1000 K / s or more, it is preferable to control the rotation speed of the base plate 131 of the turntable 130 so that the rotation speed is 800 rpm or more. By setting the rotation speed at such a speed, the scanning speed of the head unit 110 becomes 1,000,000 mm / min or more, and the cooling rate described above can be satisfied. There is no particular upper limit to the rotation speed of the turntable 130, but considering the load on the device, it is preferable that the cooling rate of the molten powder material is 10 8 The rotation speed of the turntable 130 is set to 2000 rpm or less, which is a speed that is less than K / s. The rotation speed of the turntable 130 is more preferably set to 1000 rpm or more and 2000 rpm or less.

[0038] Furthermore, for example, multiple beads (products) can be formed on the circumference of a rotary table. Furthermore, when the rotation speed of the rotary table is constant, the scanning speed increases as one moves from the center of rotation of the rotary table toward the periphery. Therefore, for example, by controlling the rotation speed of the rotary table to be constant and spraying powder material while moving the laser beam irradiation head from the center of rotation toward the periphery, it is possible to produce beads (products) with different cooling rates on the rotary table. The laser beam irradiation head can also be moved from the center of rotation toward the periphery. In other words, by providing a base plate with a rotation mechanism and a translation mechanism, it is possible to produce additively manufactured objects with metal structures with different cooling rates simply by moving the laser beam irradiation head in the radial direction of the rotary table.

[0039] The base plate 131 is provided on the upper surface of the rotary table 130 in order to form an additive product. The base plate 131 is provided parallel to the direction perpendicular to the light beam irradiation direction. In this case, it is preferable that the base plate 131 is detachable from the rotary table 130. If the base plate 131 can be detached from the rotary table 130, the additive product can be removed together with the base plate when it is to be removed. The removed additive product can be removed from the base plate 131 by machining, and the removed base plate 131 can be attached to the rotary table 130 and used again for additive manufacturing.

[0040] An example of such an additive manufacturing apparatus includes a light beam irradiation head unit, a base plate installed in the direction of light beam irradiation from the light beam irradiation head unit, in other words, on an extension of the direction of travel of the irradiated light beam, a rotary table installed below the base plate and rotating the base plate in a direction perpendicular to the light beam irradiation direction, and a base unit installed below the rotary table and moving the rotary table in a direction perpendicular to the light beam irradiation direction. In other words, an example of such an additive manufacturing apparatus includes an additive manufacturing apparatus in which the rotary table is disposed on the base unit, the light beam irradiation head unit is disposed above the rotary table, and the light beam and powder material are simultaneously irradiated and supplied from the light beam irradiation head unit toward the base plate while the rotary table is rotating.

[0041] [About the manufacturing method of additive manufacturing products] FIG. 1 shows a schematic diagram illustrating one embodiment of a method for manufacturing an additive product. The method for manufacturing an additive product includes a powder material supplying step in which a head unit 110 supplies powder material toward a base plate 131 on a rotary table 130; a melting step in which the head unit 110 irradiates the powder material supplied toward the base plate 131 with a light beam to heat the powder material above its melting point and melt it; and a solidification step in which the melted powder material that has reached the base plate 131 is air-cooled and solidified to form a bead on the base plate 131. The additive product is formed by repeating a series of steps, which are performed in this order: the powder material supplying step, the melting step, and the solidification step. It is also preferable to simultaneously irradiate and supply a light beam and powder material from the light beam irradiating head unit toward the base plate while rotating the rotary table.

[0042] In the powder material supply step, the powder material is supplied to the base plate 131 on the rotary table 130. There are no particular limitations on the method for supplying the powder material; however, the powder material can be stored in a powder material supply device, transported to the head unit 110 through a transport pipe, and supplied from the head unit 110 to the base plate 131. There are no particular limitations on the method for supplying and controlling the powder material; however, from the viewpoint of stabilizing the supply of the powder material, it is preferable to use a disk system. There are also no particular limitations on the number of containers for storing the powder material; the number can be determined according to the number of types of powder to be mixed.

[0043] In the melting step, a light beam is irradiated onto the powder material discharged toward the base plate 131, and the powder material is melted by being heated to a temperature above its melting point. It is preferable that the powder material be melted after being supplied from the head unit 110, before it reaches the base plate 131, or the moment it reaches the base plate 131. In this embodiment, in which the base plate 131 is provided on the upper surface of the turntable 130, such a melting method allows the molten powder material to adhere to the base plate 131, so that the precision of the additive manufacturing product can be increased even if the rotation speed of the turntable 130 is maintained high.

[0044] In order to irradiate the light beam onto the supply position of the powder material in this manner, the powder material and the light beam are supplied from the same head unit 110. In this case, it is preferable that the head unit 110 has a plurality of powder material discharge ports arranged on a concentric circle centered on the light beam irradiation port. In order to irradiate the powder material with a light beam in the air and cause the molten powder material to adhere to the base plate 131, it is necessary to provide the light beam irradiation port and the powder material discharge port separately. By providing a plurality of discharge ports on a concentric circle centered on the light beam irradiation port, the powder material discharged from the plurality of discharge ports joins at a point on the irradiation path of the light beam, melts, and drips toward the base plate 131.

[0045] The type of light beam is not particularly limited, but a laser beam is preferred because it provides high resolution during modeling. Other suitable light beams include electron beams and arc discharge. The output of the light beam 131 is preferably 3 kW or more and 6 kW or less, and the beam diameter φ is preferably 1 mm or more and 3 mm or less. By using such an output and beam diameter, sufficient energy density can be obtained to melt the powder material, thereby suppressing defects in the additive manufacturing product, such as pits and spatters.

[0046] In the solidification step, the molten powder material is cooled by air or inert gas and solidified to form a solidified layer 140 on the base plate 131. The cooling method for the molten powder material 110 is air cooling, and the rotation of the turntable 130 generates a scanning speed of the light beam on the base plate 131, which can reduce the heat input to the powder material and its surroundings and improve the cooling rate. The turntable 130 is set to rotate in a direction perpendicular to the direction of irradiation of the light beam, and the base plate 131 is set on the upper surface of the turntable 130 so as to be parallel to the direction perpendicular to the direction of irradiation of the light beam. At this time, in order to solidify the molten powder material 110, the cooling rate must be 10 2 K / s or more 10 8In addition, when manufacturing a wide variety of additive products, when using powder materials with low thermal conductivity or high melting points, and when obtaining additive products with a dense structure, it is desirable for the cooling rate to be even higher, more preferably 10 6 K / s or more 10 8 K / s, and more preferably less than 10 7 K / s or more 10 8 It is less than K / s.

[0047] As described above, there are no particular limitations on the shape of base plate 131. Furthermore, it is preferable that the effective radius, which is the distance from the center of rotation on base plate 131 to the light beam irradiation point, is 200 mm or more and 300 mm or less. It is preferable that the rotation speed of base plate 131 of turntable 130 be controlled so that the rotation speed is 800 rpm or more and 2000 rpm or less, and more preferably, the rotation speed is 1000 rpm or more and 2000 rpm or less.

[0048] At this time, in order to continuously perform the process of rapidly cooling the molten powder material, the powder supply step, melting step, and solidification step are performed while rotating the turntable 130. It is also preferable that the turntable 130 and the base plate 131 can be moved in a direction perpendicular to the light beam irradiation direction by the base part 120. If only the turntable 130 were used, the shape of the additive product would be limited to a cylindrical shape, but the turntable 130 can be moved horizontally by the base part 120, which increases the degree of freedom in the shape of the additive product.

[0049] According to this additive manufacturing method, additive manufacturing is performed while rotating the rotary table 130, which avoids unnecessary heat input to the powder material and base plate, allowing the molten powder material to be cooled quickly and the structure of the additive product to be adjusted to obtain an additive product with desired properties.

[0050] [About additive manufacturing] The shape of the additive product obtained by the additive manufacturing apparatus and manufacturing method of the additive product of the present invention as described above is not particularly limited. It is possible to obtain not only cylindrical or columnar shapes that follow the rotation direction of the turntable 130, but also non-rotational shapes. By using the horizontally movable base 120 to move the turntable 130 horizontally, it is possible to realize block shapes such as rectangular parallelepipeds and polygonal prisms, as well as other complex shapes. [Example]

[0051] (Experiment 1) In order to confirm the relationship between the rotation speed of the turntable and each of the molding conditions required for single bead formation in the manufacturing method of the additive manufacturing product of the present invention, tests were conducted to form a single bead by changing the scanning speed (mm / min), laser output (kW), laser spot diameter (mm), and powder amount (g / min). The metal powder used for molding was a Ni-based alloy powder with a particle size range of 45 μm to 125 μm and the composition shown in Table 1.

[0052] [Table 1]

[0053] For each test condition, printing was performed at room temperature with four scanning speeds: 10,000, 50,000, 100,000, and 1,000,000 mm / min, and the laser power (kW), laser spot diameter (mm), and powder supply rate (g / min) were varied. Figure 2(a) shows a process map of each test condition combination and whether or not bead formation was possible. Under conditions indicated by a circle (○), beads were formed normally; under conditions indicated by a triangle (△), beads were formed but with defects, and under conditions indicated by a cross (×), beads could not be formed at all.

[0054] Figure 2 shows that in order to form a bead under high scanning speed conditions, it is necessary to increase the laser power and reduce the laser spot diameter to increase the laser energy density. Furthermore, increasing the laser energy density too much can cause bead formation to fail, and it was found that in order to form a bead, the powder supply amount must be increased according to the laser energy density. For example, in Figure 2, when the laser power was changed under the conditions of a laser spot diameter of 2.0 mm, a scanning speed of 100,000 mm / min, and a powder supply amount of 44.0 g, a bead was formed at a laser power of 4 kW, but not at a laser power of 3 kW due to insufficient energy density. Furthermore, when the laser power was increased to 5-6 kW, insufficient powder supply caused bead formation, resulting in bead formation.

[0055] Among the scanning speed conditions of 10,000 mm / min and 50,000 mm / min, beads were successfully formed under the condition where the laser beam energy density was high. Since the energy density of a laser beam can be calculated by dividing the laser output by the laser spot area, it was found that beads are more likely to be successfully formed under conditions where the laser output is high and the laser spot diameter is small. On the other hand, because bead formation failed under many conditions when the laser diameter was 1 mm, it is thought that in order to form beads, it is necessary to increase the laser energy density and also the amount of powder supplied.

[0056] Figure 3 shows a comparison of the appearance of beads formed under different conditions of laser power, powder supply rate, and spot diameter when 30 layers of beads were stacked at a scanning speed of 50,000 mm / min. The conditions on the left side of Figure 3 indicate lower laser power and larger laser spot diameter, i.e., lower laser energy density and lower powder supply rate. Under the condition on the far left side of Figure 3, the low laser energy density and low powder supply rate resulted in numerous pit-like defects in the bead, and the bead itself was flattened. It can be seen that increasing the laser energy density and powder supply rate improved the bead condition. Finally, under the conditions of 6 kW laser power, 2.0 mm laser spot diameter, and 44.0 g / min powder supply rate, the pit-like defects disappeared, and the bead shape itself was no longer sagging or flattened.

[0057] Next, we investigated the cross-sectional structure of the bead obtained under the scanning speed conditions of 10,000 mm / min, 100,000 mm / min, and 1,000,000 mm / min, which yielded the best shape. We then examined the effect of the scanning speed (i.e., the cooling rate) on the cross-sectional structure of the bead. Figures 2(b)–(d) show the cross-sectional structure of the bead obtained under each scanning speed. Figure 2(b) shows the cross-sectional structure of the bead obtained under the scanning speed of 10,000 mm / min, laser power of 3 kW, laser spot diameter of 2.0 mm, and powder supply rate of 44.0 g / min. Figure 2(c) shows the cross-sectional structure of the bead obtained under the scanning speed of 100,000 mm / min, laser power of 6 kW, laser spot diameter of 2.0 mm, and powder supply rate of 44.0 g / min. Figure 2(d) shows the cross-sectional structure of the bead obtained under the scanning speed of 1,000,000 mm / min, laser power of 6 kW, laser spot diameter of 1.0 mm, and powder supply rate of 100.0 g / min.

[0058] As mentioned above, all beads used for cross-sectional observation were formed by melting and solidifying the Ni-based alloy powders listed in Table 1. The cross-sectional images shown in Figures 2(b), (c), and (d) show primary dendritic structures and secondary dendritic structures that are finer than the primary dendritic structures at all scanning speeds: 10,000 mm / min, 100,000 mm / min, and 1,000,000 mm / min. Furthermore, the spacing between the arms of the secondary dendritic structures decreased with increasing scanning speed (i.e., the cooling rate of the bead), resulting in a finer structure. The measured spacing between the arms of the secondary dendritic structures was 3 μm at a scanning speed of 10,000 mm / min, 1 μm at a scanning speed of 100,000 mm / min, and 0.2 μm at a scanning speed of 1,000,000 mm / min. The alloy with the composition shown in Table 1 is a Ni-based alloy known as 718 alloy, and the relationship between the spacing of the arms of the secondary dendrite structure and the cooling rate of 718 alloy is disclosed in the non-patent document "Nobumitsu Shohoji: Roles of Unstable Chemical Species and Non-Equilibrium Reaction Routes on Properties of Reaction Product-A Review, Journal of Surfaces and Interfaces of Materials, 2, 182-205 (2014)." Using this relationship, the relationship between the scanning speed and cooling rate of the additive manufacturing equipment was determined. As a result, at a scanning speed of 10,000 mm / min, the cooling rate was approximately 10 3 K / s, and a scanning speed of 100,000 mm / min is approximately 10 4 K / s, and a scanning speed of 1,000,000 mm / min is approximately 10 6 It was K / s.

[0059] Conventional DED additive manufacturing equipment requires 10 6 It is difficult to achieve a cooling rate of more than 10 K / s, but the additive manufacturing device of the present invention can achieve a cooling rate of approximately 10 K / s at a scanning speed of 1,000,000 mm / min. 6 A cooling rate of 1000 K / s was achieved. [Explanation of symbols]

[0060] 100: Additive manufacturing equipment 110: Head 120: Base 130: Rotating table 131: Base plate 140: Solidified layer

Claims

1. a powder material supplying step of supplying powder material toward a base plate on a rotary table; a melting step of irradiating a light beam onto the powder material supplied toward the base plate to melt the powder material; a solidification step of depositing the molten powder material on the base plate, air-cooling the molten powder material, and solidifying the molten powder material to form a bead on the base plate; The powder material supplying step, the melting step, and the solidifying step are performed while rotating the rotary table in a direction perpendicular to the irradiation direction of the light beam, and these steps are repeated to form an additive product. A method for producing an additive product, characterized by:

2. The method for manufacturing an additive product according to claim 2, characterized in that the light beam is irradiated and the powder material is supplied to a position at a distance of 200 mm or more from the rotation center of the rotary table, and the rotary table controls the rotation of the base plate so that the rotation speed is 800 rpm or more and 2000 rpm or less.

3. 2. The method for manufacturing an additive product according to claim 1, wherein the light beam is a laser beam, the output of the laser beam is 2 kW or more and 6 kW or less, and the beam diameter φ of the laser beam on the base plate is 1 mm or more and 3 mm or less.

4. 2. The additive manufacturing method of claim 1, wherein the base plate rotates to air-cool the molten powder material deposited on the base plate.

5. 10. The additive manufacturing method of claim 1, wherein the powder material is a Ni-based alloy powder.

6. a light beam irradiation head unit that irradiates a light beam and supplies a powder material; a base plate disposed in the irradiation direction of the light beam from the light beam irradiation head unit; a rotary table disposed below the base plate and configured to rotate the base plate in a direction perpendicular to the irradiation direction of the light beam; a base portion disposed below the rotary table and configured to move the rotary table in a direction perpendicular to the light beam irradiation direction, While rotating the rotary table, the light beam from the light beam irradiation head unit and the powder material are simultaneously irradiated and supplied toward the base plate. An additive manufacturing device characterized by:

7. The additive manufacturing device according to claim 6, wherein the base unit controls the light beam irradiation position on the base plate so that the distance from the rotation center of the rotary table to the light beam irradiation position is 200 mm or more, and the rotary table controls the rotation of the base plate so that the rotation speed is 800 rpm or more and 2000 rpm or less.

8. The additive manufacturing device of claim 6, wherein the light beam is a laser beam, the output of the laser beam is 2 kW or more and 6 kW or less, and the beam diameter φ of the laser beam on the base plate is 1 mm or more and 3 mm or less.

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