Directed Energy Deposition (DED) Metal 3D Printing Method

Abstract

To provide a female thread by packing a hexagonal nut as a ready-made product into a metal 3D molded object.SOLUTION: When an engaging recessed part 8 to be buried with a ready-made product at the inside is molded, the molding of a metal 3D molded object 4 is temporarily stopped, a hexagonal nut 1 as the ready-made product is engaged and held to the engaging recessed part 8, and thereafter, the molding of the metal 3D molded object 4 is restarted, so that the hexagonal nut 1 is packed therein to form a female thread 1a. In this way, the metal 3D molded object by a directed energy deposition method having the correct female thread 1a formed can be obtained.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present invention relates to a metal 3D modeling method using directed energy deposition. [Background technology]

[0002] Generally, known metal 3D modeling methods include a powder bed fusion method and a directed energy deposition method (see, for example, Patent Document 1 or Patent Document 2).

[0003] That is, in the powder bed fusion metal 3D printing method, powder metal is thinly layered on a bed, and the part hit by the laser beam melts and solidifies. The bed then lowers by the thickness of one layer, and another layer of powder metal is layered. The same process is repeated to create a metal 3D object.

[0004] On the other hand, in the metal 3D printing method using the directed energy deposition method, the metal material sprayed from the printing head is melted and solidified by the laser beam emitted from the printing head to form a model. After that, the printing head moves and one layer of the model is formed, and then the metal material sprayed from the printing head is melted on top of the previous model by the laser beam sprayed from the printing head to form a new model. After that, the same operation is performed to print the metal 3D model. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2018-527484 [Patent Document 2] US Patent Application Publication No. 2003 / 0206820 Summary of the Invention [Problem to be solved by the invention]

[0006] For example, when forming a female thread into which a male thread such as a bolt is to be screwed, a metal 3D printing method using powder bed fusion requires secondary processing in which a metal 3D object is first fabricated with a pilot hole in the area where the female thread is to be formed, and then a female thread is formed in the pilot hole in this object using a tap or the like.

[0007] On the other hand, in the metal 3D printing method using the directed energy deposition method, it is possible to form a female thread whose axis is perpendicular to the printing surface (XY plane), but there are limitations on the pitch of the female thread, and molten powder residue is likely to remain in the female thread part. Moreover, as with the metal 3D printing method using the powder bed fusion method, it is not possible to form a female thread whose axis is parallel to the printing surface, and secondary processing such as tapping is required.

[0008] Furthermore, with any metal 3D printing method, secondary processing such as attaching an RF tag with embedded IC information on the object may be required after the object is completed, which is extremely troublesome.

[0009] Therefore, the present invention aims to provide a metal 3D printing method using directed energy deposition that does not have such problems and that does not require secondary processing by incorporating pre-made items such as hex nuts with female threads or RF tags into metal 3D models. [Means for solving the problem]

[0010] The present invention solves this problem by providing a metal 3D printing method using directed energy deposition, which is characterized in that the production of the metal 3D model is temporarily stopped when an engagement recess is formed, a pre-made product is engaged and held in the engagement recess, and then the production of the metal 3D model is resumed, thereby incorporating the pre-made product.

[0011] In such an embodiment of the present invention, it is preferable that the engagement recess has the same or approximately the same shape as the volume of the pre-made product to be engaged therewith, or the same or approximately the same shape as a part of the volume of the pre-made product. When there are multiple types of pre-made products, it is preferable to temporarily stop the modeling of the metal 3D modeled object when the engagement recesses for engaging the various pre-made products are formed. Furthermore, it is preferable that the pre-made product is a polygonal nut, for example, a hexagonal nut or a square nut, and it is preferable that the pre-made product is a hexagonal nut or a square nut whose axis is perpendicular to the modeling surface (XY plane) of the metal 3D modeled object, or a hexagonal nut or a square nut whose axis is parallel to the modeling surface. It is also preferable that the pre-made product is an RF tag. Effect of the Invention

[0012] According to the metal 3D printing method using the directed energy deposition method of the present invention, a molded object is obtained in a state in which a pre-made product is engaged with the engagement recess, and when the pre-made product is ready to be engaged with the engagement recess, the molding of the molded object is temporarily stopped, and then the pre-made product engages with the engagement recess and molding is resumed, thereby forming a metal 3D printed object with a pre-made product built in. Therefore, when the pre-made product is a hexagonal nut or a square nut, a secondary process for threading is not required, there are no restrictions on the pitch of the female screw, and no molten powder residue remains on the female screw portion, and the female screw can be easily and accurately obtained. Moreover, not only when the axis of the female screw is perpendicular to the printing surface (XY plane) of the metal 3D printed object, but also when the axis of the female screw is parallel to the printing surface, which could not be obtained without secondary processing in the conventional metal 3D printing method using the directed energy deposition method, it is possible to easily obtain the female screw. Furthermore, in addition to nuts, various pre-made products, including RF tags storing product information, can be built in, and these can be molded as part of the metal 3D printed object without the need for secondary processing. In this way, the metal 3D printing method using the directed energy deposition method of the present invention can incorporate a variety of prefabricated products, and its practical value is extremely great. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing an embodiment of a metal 3D modeling method using a directed energy deposition method according to the present invention, in a modeling start state. [Diagram 2] FIG. 2 is a cross-sectional view of a first modeling stopped state in which modeling is temporarily stopped thereafter. [Diagram 3] FIG. 3 is a cross-sectional view of the first modeling stopped state in which the hexagonal nut is engaged with the engagement recess. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. 5 is a cross-sectional view showing a state in which modeling is resumed thereafter. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 7 is a cross-sectional view of a second modeling stopped state in which modeling thereafter is temporarily stopped. [Figure 8] FIG. 8 is a cross-sectional view of the second modeling stopped state in which the hexagonal nut is engaged with the engagement recess. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. [Figure 10] FIG. 10 is a cross-sectional view showing a state in which modeling is resumed thereafter. [Figure 11] FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. [Figure 12] FIG. 12 is a cross-sectional view showing the final metal 3D model. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a metal 3D modeling method using a directed energy deposition method according to the present invention will be specifically described with reference to the drawings.

[0015] FIG. 1 is a cross-sectional view of a modeling start state showing one embodiment of a metal 3D printing method using a directed energy deposition method of the present invention, FIG. 2 is a cross-sectional view of a first modeling stop state in which subsequent modeling is temporarily stopped, FIG. 3 is a cross-sectional view of the first modeling stop state in which a hexagonal nut is engaged with an engagement recess, FIG. 4 is a cross-sectional view along line IV-IV of FIG. 3, FIG. 5 is a cross-sectional view showing a state in which modeling is resumed thereafter, FIG. 6 is a cross-sectional view along line VI-VI of FIG. 5, FIG. 7 is a cross-sectional view of a second modeling stop state in which subsequent modeling is temporarily stopped, FIG. 8 is a cross-sectional view of the second modeling stop state in which a hexagonal nut is engaged with an engagement recess, FIG. 9 is a cross-sectional view along line IX-IX of FIG. FIG. 10 is a cross-sectional view showing the state after modeling has been resumed, FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. 10, and FIG. 12 is a cross-sectional view showing the final metal 3D model.

[0016] In this embodiment, as shown in Fig. 12, hexagonal nuts 1, 2 and an RF tag (not shown) are selected as prefabricated objects, and a metal 3D model 4 incorporating the hexagonal nuts 1, 2 and the RF tag is produced by a metal 3D modeling method using a directed energy deposition method. Note that multiple hexagonal nuts 1, 2 are embedded, but for convenience, only one is shown in the figure.

[0017] That is, as shown in Figures 1 to 11, an apparatus for implementing a metal 3D printing method using the directed energy deposition method includes a printing head 5 having an ejection nozzle for a laser beam 5a and metal material (metal powder, metal wire, etc.) 5b, a bed 6 whose upper surface serves as a printing base 6a, and a drive device for these (not shown). The laser beam 5a is locally irradiated onto the printing base 6a, and the metal material 5b is concentratedly injected into the molten pool formation area, and the metal 3D object 4 is melted and deposited on the XY plane.

[0018] First, as shown in FIG. 1, the bolt insertion hole 7 is formed on the substrate 5a in the XY plane by the modeling head 5, and then the engagement recess 8 is formed concentrically with the bolt insertion hole 7.

[0019] 2, when the engagement recess 8 (hereinafter referred to as the "first engagement recess 8") assumes a shape that fully engages with the hexagonal nut 1 (hereinafter referred to as the "first hexagonal nut 1") with its axis perpendicular to the forming surface (XY plane), forming is temporarily stopped (first forming stopped state). Then, in the first forming stopped state, the first hexagonal nut 1 is fully and tightly engaged with the first engagement recess 8 as shown in FIG. 3 and FIG. 4(A). It is preferable that the first engagement recess 8 has a shape identical to the volume of the first hexagonal nut 1 as shown in Figure 4(A) and is a shape that tightly engages the first hexagonal nut 1 all over, but it may have a shape identical or approximately identical to a part of the volume of the first hexagonal nut 1 as shown in Figure 4(B) and engages a part of the first hexagonal nut 1 so as not to rotate, or as shown in Figure 4(C), it may have a shape that is approximately the same as the volume of the first hexagonal nut 1 and is slightly larger than the volume of the first hexagonal nut 1 to take into account its expansion.

[0020] When the first hexagonal nut 1 is engaged with the first engagement recess 8, the shaping by the shaping head 5 is resumed, and as shown in Figs. 5 and 6, the first hexagonal nut 1 engaged with the first engagement recess 8 is fitted inside the shaping object 4, and a bolt end introduction hole 9 is formed which is concentric with the first engagement recess 8 and has the same diameter as the bolt insertion hole 7. The bolt insertion hole 7 and the bolt end introduction hole 9 are slightly larger in diameter than the female thread 1a of the first hexagonal nut 1. The first hexagonal nut 1, the bolt insertion hole 7, the first engagement recess 8, and the bolt end introduction hole 9 are installed at the same height and in the same shape as required, as in the illustrated example. In the illustrated example, a conical cover is formed on the upper part of the bolt end introduction hole 9 to isolate the outside from the inside, but in the case of a shaping object that does not particularly need to be isolated, it is not necessary to form the upper part of the bolt end introduction hole 9.

[0021] Further, the shaping by the shaping head 5 is continued, and as shown in FIG. 7, when the bolt insertion hole 10, the engagement recess 11, and the bolt end introduction hole 12 whose axes are parallel to the XY plane are partially formed, shaping is temporarily stopped (second shaping stop state). In the second shaping stop state, as shown in FIG. 8 and FIG. 9(A) or FIG. 8 and FIG. 9(B), the engagement recess 11 (hereinafter referred to as the "second engagement recess 11") has a shape that is the same as a part of the volume of the hexagonal nut 2 (hereinafter referred to as the "second hexagonal nut 2") whose axis is perpendicular to the YZ plane, that is, the lower half of the second hexagonal nut 2. The second engagement recess 11 has a shape that can be tightly engaged in a state in which it can be inserted and removed. The bolt insertion hole 10, the engagement recess 11, and the bolt end introduction hole 12 are concentric, and the bolt insertion hole 10 and the bolt end introduction hole 12 are slightly larger in diameter than the female thread 2a of the second hexagonal nut 2. 9(C) or 9(D), the second engagement recess 11 may be shaped to fully engage the second hexagonal nut 2, with spaces 12a, 12b being formed between the second hexagonal nut 2 and the upper half of the second hexagonal nut 2. The second hexagonal nut 2, the bolt insertion hole 10, the second engagement recess 11, and the bolt end introduction hole 12 may be arranged in the same manner as shown in the drawings, with one or more of them being installed at the same height position and in the same shape, as required.

[0022] When the second hexagonal nut 2 is engaged with the second engagement recess 11, shaping by the shaping head 5 is resumed, and as shown in Fig. 10, the bolt introduction hole 10 and the bolt end introduction hole 12 are completed, and the second hexagonal nut 2 is fitted inside the second engagement recess 11. The second hexagonal nut 2 is completely embedded as shown in Fig. 10 and Fig. 11(A) or Fig. 10 and Fig. 11(B). When the second engagement recess 11 is one in which the upper half of the second hexagonal bolt 2 engages with spaces 12a and 12b as shown in Fig. 9(C) or Fig. 9(D), the second hexagonal nut 2 is fitted inside with spaces 12a and 12b as shown in Fig. 11(C) or Fig. 11(D).

[0023] Then, as modeling continues using the modeling head 5, the obtained metal 3D model 4 can have bolts 14, 15 screwed into the female threads 1a of the first hexagonal nuts 1 and the female threads 2a of the second hexagonal nuts 2 that are perpendicular to each other, as shown in Fig. 12, and can have another member through which the bolts 14, 15 are inserted or another member integrated with the bolts 14, 15 attached. Also, information about the model 4 can be obtained from the RF tag.

[0024] Thus, according to the metal 3D printing method using the directed energy deposition method of the present invention, the engagement recesses 8, 11 are engaged, and each time the first hexagonal nut 1, the second hexagonal nut 2, and the RF tag are engaged therewith, the printing of the metal 3D printed object is temporarily stopped, whereby the first hexagonal nut 1, the second hexagonal nut 2, and the RF tag can be embedded. Therefore, the embedded first hexagonal nut 1 and the second hexagonal nut 2 can accurately form the female threads 1a, 2a without the need for secondary processing using a tap or the like, and in particular, the female thread 2a whose axis is parallel to the printing surface (XY plane), which was not possible in the past, can be realized by embedding the second hexagonal nut 2. In addition, by embedding the RF tag, information on the metal 3D printed object 4 can be obtained without the need for secondary processing.

[0025] The configuration of the present invention is not limited to the above-described embodiment, and can be appropriately improved or modified without departing from the basic principles of the present invention.

[0026] For example, in the above embodiment, a first hexagonal nut 1 and a second hexagonal nut 2 were used, but as a nut having female threads 1a and 2a, a square nut (a nut with a square outer shape) that does not rotate when installed inside the molded object 4 can also be used.

[0027] The ready-made product to be engaged with the engagement recess may be various RF tags of various shapes on which information on the molded product (product information after molding, etc.) is recorded. In this case, it is preferable that the thickness of the upper surface of the engagement recess into which the RF tag is engaged is a thickness that allows radio waves to reach, for example, about 1 mm to 2 mm.

[0028] In addition, in the above-described embodiment, the manufacturing process had to be stopped three times to fit the first hexagonal nut 1, the second hexagonal nut 2, and the RF tag into the metal 3D model 4. However, if there is only one type of prefabricated object to be fitted, the manufacturing process only needs to be stopped once, and if there are two or four or more types, the manufacturing process only needs to be stopped two or four or more times. [Explanation of symbols]

[0029] 1 First hexagon nut (hexagon nut) 1a Female thread 2 Second hex nut (hex nut) 2a Female thread 4 Metal 3D objects 5 Modeling head 5a Laser beam 5b Metal materials 6 Beds 8 First engagement recess (engagement recess) 11 Second engagement recess (engagement recess)

Claims

1. A method for producing a metal 3D object by locally irradiating a laser beam and intensively pouring metal material into a molten pool forming portion, and melting and solidifying the metal material with the laser beam; When an engagement recess for embedding a pre-made product inside the metal 3D model is formed, the modeling of the metal 3D model is temporarily stopped to engage and hold the pre-made product in the engagement recess, and then the modeling of the metal 3D model is resumed to embed the pre-made product inside the metal 3D model. A metal 3D modeling method using a directed energy deposition method, characterized in that the prefabricated product is a prefabricated product having a female thread or an RF tag.

2. The prefabricated product is a prefabricated product having a female thread, The metal 3D printing method using directed energy deposition as described in claim 1, characterized in that the prefabricated product is a polygonal nut whose axis is parallel to the printing surface.

3. The ready-made product is an RF tag, 2. A metal 3D modeling method using directed energy deposition as described in claim 1, characterized in that the thickness of the upper surface of the engagement recess in which the RF tag is engaged is 1 mm or more and 2 mm or less.

4. The metal 3D printing method using directed energy deposition according to claim 1 , wherein the engagement recess has a shape that is the same as or approximately the same as a volume of the pre-made product to be engaged therewith.

5. The metal 3D printing method using directed energy deposition according to claim 1 , wherein the engagement recess has a shape that is the same as or approximately the same as a part of the volume of the pre-made product to be engaged therewith.

6. The metal 3D printing method using a directed energy deposition method according to any one of claims 1 to 5, characterized in that, when there are multiple types of pre-made products, printing of the metal 3D model is temporarily stopped when an engagement recess for engaging the various pre-made products is formed.

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