Reprocessing methods for metal products

Abstract

A method for reworking a metal product comprises: a welding step of welding a dummy component to the metal product; a reworking step of reworking the metal product while the metal product is supported by a first support portion and the dummy component is supported by a second support portion; and a removal step of removing the dummy component from the metal product after the reworking step. This method allows the metal product to be fixed and reworked regardless of its shape.

Description

Technical Field

[0001] The present invention relates to a method for reprocessing a metal product using a machine tool. Background Art

[0002] Laser lamination methods (additive manufacturing) that form a structure on the surface of a workpiece while supplying laser light and metal powder are becoming increasingly popular. For example, Patent Document 1 proposes a laser lamination method that forms a structure on the surface of a workpiece using a laser lamination device having an irradiation section for irradiating a laser beam to an irradiation area, a supply section for supplying metal powder to the irradiation area, and a movement mechanism for relatively moving the head and the workpiece. The method is characterized in that the structure is formed by performing at least one lamination and remelting process. The lamination and remelting process includes: a lamination step in which, while laser irradiation and metal powder supply are being performed, the head is moved relative to the workpiece to perform lamination multiple times, thereby forming a laminated structure composed of multiple layers on the workpiece; and a remelting step in which, after the lamination step, the head is moved relative to the workpiece while laser irradiation is being performed but metal powder is not being supplied, thereby irradiating the surface of the laminated structure with laser light to remelt it.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2019-157149 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] There is a desire to repair metal parts (existing products) that have been processed into shapes with specified functions. For example, large metal parts such as rocket nozzles and turbine blades are not discarded after use, but are reprocessed or repaired multiple times and reused.

[0008] However, when a metal part that has already been processed into a shape with a predetermined function is reprocessed using a machine tool, it may be difficult to support the metal part using the machine tool's predetermined support unit. For example, a machine tool may include a support unit with a chuck mechanism to secure the workpiece. Such a support unit may not be able to clamp the metal part that has already been processed into a shape with a predetermined function, making it difficult to stably secure the metal part.

[0009] Means used to solve problems

[0010] A technical solution of the present invention relates to a method for reprocessing a metal product, which is a method for reprocessing a metal product, comprising: a welding process of welding a dummy component to the above-mentioned metal product; a reprocessing process of reprocessing the above-mentioned metal product in a state where the above-mentioned metal product is supported by a first support part and the above-mentioned dummy component is supported by a second support part; and a removal process of removing the above-mentioned dummy component from the above-mentioned metal product after the above-mentioned reprocessing process.

[0011] Effects of the Invention

[0012] The metal product can be fixed and reprocessed without being restricted by its shape.

[0013] The novel features of the present invention are described in the claims, but the present invention, both in terms of structure and content, together with other objects and features of the application, will be better understood from the following detailed description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a front view schematically showing the interior of an example of a machine tool used in the present embodiment.

[0015] Figure 2 This is a perspective view showing the state of a machining space during AM machining performed by a machine tool.

[0016] Figure 3 This is a diagram showing an example of the configuration of a powder feeder and a laser oscillator.

[0017] Figure 4A It is a diagram showing a metal product supported by a first supporting portion and a second supporting portion.

[0018] Figure 4B This is a diagram showing a state where a cut band is formed on a metal product supported by a first support portion.

[0019] Figure 4C This is a diagram showing a state in which a metal product supported by a first supporting portion and a dummy member supported by a second supporting portion are welded.

[0020] Figure 4D This is a diagram showing a state in which a metal product is reprocessed in a state in which the metal product is supported by the first support portion and the dummy member is supported by the second support portion.

[0021] Figure 4E This figure shows the state where a dummy component is cut away from a metal product.

[0022] Figure 4F This figure shows the metal product after the dummy parts have been removed.

[0023] Figure 5This is a diagram showing a scenario of another embodiment of the reprocessing method of a metal product.

[0024] Figure 6 This is a diagram showing one scenario of an embodiment of a reprocessing method for another metal product.

[0025] Figure 7 This is a diagram showing a scenario of another embodiment of a reprocessing method for another metal product.

[0026] Figure 8 This is a conceptual diagram showing a hypothetical minimum rectangular parallelepiped that can accommodate metal products. DETAILED DESCRIPTION

[0027] The method for reprocessing a metal product according to the present embodiment includes: (i) a welding process of welding a dummy component to the metal product; (ii) a reprocessing process of reprocessing the metal product while the metal product is supported by a first support portion and the dummy component is supported by a second support portion; and (iii) a removal process of removing the dummy component from the metal product after the reprocessing process.

[0028] Here, "support" includes concepts such as fixing and holding, and generally refers to contact with a metal product (or a dummy component) to suppress the vibration, swing, tremor and other movements of the metal product.

[0029] Furthermore, a "metal product" can be any existing product, such as a metal part, at least partially made of metal. An existing product is a structure that has been processed into a shape that has a predetermined function. In other words, in the reprocessing method of this embodiment, the metal product being reprocessed already has the predetermined function before the dummy component is welded. However, it is a metal product that requires reprocessing (or repair).

[0030] The metal product may also be a structure in which dummy components have been welded to an existing product. That is, in the method according to this embodiment, the metal product to be reprocessed may be a structure that has been processed into a shape having a predetermined function before the dummy components are welded, and a combination of other dummy components. In this case, at least two dummy components are welded to the metal product during reprocessing.

[0031] Specific examples of metal products include, but are not particularly limited to, relatively large metal products used in the aviation, aerospace, and energy industries, such as rocket nozzles and turbine blades. Relatively large metal products are often difficult to securely support or secure using conventional support components of machine tools.

[0032] The material of the metal product may be, for example, at least one selected from the group consisting of titanium-based alloys, cobalt-based alloys, and nickel-based alloys, but is not limited thereto.

[0033] On the other hand, when metal products are reprocessed, it is necessary to support or fix the metal products firmly in order to improve the precision of the reprocessing. Otherwise, the metal products will vibrate in the process of reprocessing the metal products, and the precision of the reprocessing will decrease.

[0034] When processing a workpiece (i.e., the raw material for the metal product) before it becomes a metal product, it is formed into a shape that is easily supported by a support component on a machine tool. Examples of such support components include the spindle's chuck mechanism, workpiece support, stabilizer support, and tailstock. However, metal products that have been processed into a shape that fulfills a specific function may sometimes be difficult to support with such support components.

[0035] In contrast, by pre-welding a dummy component of a shape that is easier to support with the support portion to the metal product, the support portion can be used to facilitate the metal product's support. For example, by supporting the metal product with the first support portion and the dummy component welded to the metal product with the second support portion, the metal product can be reprocessed while being securely fixed. Since the dummy component is no longer necessary after the metal part performs its intended function, it can be removed from the metal product after reprocessing is completed.

[0036] The welding process and the reprocessing process can also be carried out in the processing space of a machine tool equipped with a welding torch for the welding process and a tool spindle used in the reprocessing process. The welding method is not particularly limited, and examples thereof include laser welding, electron beam welding, arc welding, etc. In this case, the machine tool is a hybrid processing machine capable of performing additional processing (additive manufacturing) (hereinafter referred to as AM processing) of a workpiece or a metal product and subtractive processing (subtractive manufacturing) (hereinafter referred to as SM processing) of a workpiece or a metal product. The machine tool has, as a function of SM processing, for example, a turning function using a fixed tool and a milling function using a rotating tool.

[0037] When the machine tool is a compound lathe, one of the first and second supporting parts may be a chuck mechanism provided on a main spindle (the first main spindle). Alternatively, the other of the first and second supporting parts may be a workpiece support, a tailstock, a stabilizer support, or a chuck mechanism provided on a main spindle different from the first main spindle (the second main spindle).

[0038] In hybrid machines with AM processing capabilities, the welding process is most efficiently performed using DED (Directed Energy Deposition), a metal layering method that uses directional energy deposition. Hybrid machines with DED AM processing capabilities, for example, can selectively deposit metal powder onto desired locations on metal products and easily weld dummy parts to metal products of various shapes.

[0039] Below, with reference to the attached Figure 1 An example of a machine tool that can be used in the metal product reprocessing method according to the present invention is described. In the description of each embodiment, terms indicating directions (e.g., "up and down," "left and right," and "X-axis, Y-axis, Z-axis," etc.) are used as appropriate. However, these terms are for illustrative purposes only and do not limit the present invention. Furthermore, in the various figures, the shapes and dimensions of the various components of the machine tool are not necessarily shown to the same scale. Furthermore, the same reference numerals are used to represent the same components in the various figures.

[0040] Figure 1 It is a front view schematically showing the interior of an example of a machine tool used in the present embodiment. Figure 2 This is a perspective view showing the conditions within a machining space 200 during AM machining performed by a machine tool 100. The machine tool 100 is a hybrid machine equipped with both AM machining capabilities and SM machining capabilities for a workpiece W. Hybrid machines include, for example, lathes, vertical or horizontal machining centers, multi-tasking machines with both turning capabilities using fixed tools and milling capabilities using rotary tools, and machine tools equipped with AM machining capabilities, such as five-axis machines controlled by two or more rotary axes in addition to the X, Y, and Z axes. However, the machine tool is not limited to these.

[0041] First, the overall structure of the machine tool 100 will be described. The machine tool 100 includes a first spindle stock 110 , a second spindle stock 120 , a tool spindle (first tool stock) 130 , a second tool stock 140 , an additional machining head 150 , and a bed 160 .

[0042] The bed 160 is a base member that supports the first spindle stock 110, the second spindle stock 120, the tool spindle 130, and the second tool rest 140. The machine tool 100 is installed on a factory floor or the like via the bed 160. The first spindle stock 110, the second spindle stock 120, the tool spindle 130, and the second tool rest 140 are located in a machining space 200 surrounded by a cover 210, also known as a baffle.

[0043] exist Figure 1In the figure, the first spindle stage 110 and the second spindle stage 120 are arranged so as to face each other in the Z-axis direction. The first spindle stage 110 and the second spindle stage 120 respectively have a first spindle 111 and a second spindle 121 for rotating the workpiece W during turning using a fixed tool. The first spindle 111 and the second spindle 121 are respectively rotatable around a rotation axis parallel to the Z-axis. The second spindle stage 120 is movable in the Z-axis direction. The first spindle 111 and the second spindle 121 are provided with a first chuck mechanism 111a and a second chuck mechanism 121b for detachably holding the workpiece W. The spindles having the chuck mechanism can be used as a first support portion for supporting the metal product W and a second support portion for supporting the dummy component D.

[0044] The tool spindle 130 rotates the rotary tool during milling. The tool spindle 130 is rotatable about a rotation axis parallel to the vertically extending X-axis. The tool spindle 130 is equipped with a detachable mechanism for detachably retaining the rotary tool. The tool spindle 130 is movable in the Y-axis, which is perpendicular to the Z-axis and extends horizontally. Furthermore, the tool spindle 130 is rotatable about a rotation axis parallel to the Y-axis.

[0045] The tool spindle 130 is supported on the bed 160 by a bed post (not shown) or the like. The tool spindle 130 is movable in the X-axis direction along the bed post. The bed post is movable in the Z-axis direction.

[0046] Figure 1 The second tool rest 140 shown is a tower-type tool rest equipped with multiple fixed tools for turning. Multiple fixed tools are radially mounted on the periphery of the tower-type tool rest via tool holders. The second tool rest 140 is rotatable about an axis parallel to the Z axis via a rotating portion 142. Rotating the rotating portion 142 allows the desired fixed tool to be positioned at the machining position of the workpiece W. The second tool rest 140 is movable in the X-axis and Z-axis directions.

[0047] The machine tool 100 includes a DED (deformation and deformation) AM processing head 150. The AM processing head 150 functions as a welding torch and is connected to a cable 230 for attaching metal material and guiding a laser beam. The AM processing head 150 includes a nozzle that supplies metal material from the cable 230 to a workpiece W and irradiates the metal material and workpiece W with a laser beam. For example, the heat of the laser beam causes the workpiece W to partially melt, and metal powder is supplied to the melted portion to melt it together. The metal powder then solidifies, resulting in metal lamination. Examples of metal materials include powders or wires of stainless steel, nickel-based alloys, titanium-based alloys, and the like.

[0048] The AM machining head 150 is attachable to and detachable from the tool spindle 130. During AM machining, the AM machining head 150 is attached to the tool spindle 130. The tool spindle 130 can be moved in the X, Y, and Z axes by the various movement mechanisms described above. Similar to the movement of the tool spindle 130, the AM machining head 150 can also be moved in the X, Y, and Z axes. During SM machining, the AM machining head 150 can be detached from the tool spindle 130.

[0049] Figure 3 This figure shows an example of the configuration of the powder feeder 300 and laser oscillator 400, which introduce metal powder and a laser beam into the cable 230. The cable 230 houses piping for transferring metal powder and carrier gas to the AM processing head 150 and an optical fiber for guiding the laser beam to the AM processing head 150. The powder feeder 300 supplies metal powder to the cable 230. The laser oscillator 400 oscillates laser light. The oscillated laser light is guided into the cable 230, formed into a beam, and then emitted from the nozzle of the AM processing head 150.

[0050] The powder feeder 300 includes a main tank 310, a buffer tank 330, a powder supply unit 340, and an inert gas supply unit 350. The main tank 310 stores metal powder and delivers it from a lower outlet at appropriate times. The delivered metal powder is conveyed to the buffer tank 330 along with a carrier gas, where it is temporarily stored before being conveyed to the powder supply unit 340. In the powder supply unit 340, the metal powder and carrier gas are mixed and then directed toward the cable 230. The carrier gas is an inert gas supplied from the inert gas supply unit 350.

[0051] (First embodiment)

[0052] Next, refer to Figures 4A to 4F A further description will be given of a method for reprocessing a metal product using the above-described machine tool.

[0053] First, the welding process (i) of welding the dummy component to the metal product will be described. This welding process includes: (a) supporting the metal product with a first support portion within the processing space; (b) supporting the dummy component with a second support portion within the processing space; and (c) welding the metal product supported by the first support portion to the dummy component supported by the second support portion.

[0054] Furthermore, the welding process may include: (A) welding the cut strip (i.e., the cut allowance) on the metal product; and (B) welding the dummy component on the cut strip. In this case, by effectively utilizing the cut strip, the size reduction of the metal product can be suppressed.

[0055] Specifically, in step (a), if Figure 4AAs shown, a predetermined end portion (hereinafter referred to as the first end portion) of the metal product W1 to be reprocessed is gripped and fixed by the first chuck mechanism 111a of the first spindle 111 serving as the first supporting portion. The first end portion gripped by the first chuck mechanism 111a can be selected from a portion having a shape that is easiest to grip according to the metal product W1. In addition, if there is no portion on the metal product W1 that can be gripped by the first chuck mechanism 111a, it is sufficient to weld a dummy component of a shape that is easy to grip by the first chuck mechanism 111a to the metal product W1 in advance, and then grip it with the first chuck mechanism 111a using the dummy component as the first end portion. That is, the metal product W1 may also be a combination of a metal product W1 that has been processed into a shape having a predetermined function and a dummy component. In addition, the metal product W1 shown in the figure is, for example, a rocket nozzle, but is not limited to this.

[0056] Figure 4B The figure shows a state where a cutting band Wa is welded to the second end portion of the metal product W1, which is opposite to the first end portion. In the example shown, the cutting band Wa is formed along the entire circumference of the circular edge of the metal product W1, which serves as the second end portion. The position and size of the cutting band Wa are not particularly limited. The welding of the cutting band Wa is performed using the AM processing head 150 by the DED method. Metal powder is sprayed from the nozzle of the AM processing head 150, and a laser beam is emitted. The metal powder and the second end portion of the metal product W1 are melted by the heat of the laser beam, thereby performing the welding of the metal layered shape.

[0057] In addition, the formation of the cutting strip Wa may be performed as needed and may be omitted.

[0058] Figure 4C The figure shows the welding of a dummy component D1 to a cutting strip Wa welded onto a metal product W1. The shape of the dummy component is not particularly limited; the dummy component D1 shown in the figure is composed of a disc-shaped component and a cylindrical component protruding from one of its central surfaces. The disc-shaped component is sized to be welded to the cutting strip Wa formed on the second end of the metal product W1. The cylindrical component is gripped and secured by the second chuck mechanism 121a of the second spindle 121, which serves as the second support. The cutting strip Wa and the dummy component D1 are welded by adjusting the positions of the second spindle 121 in the Z and X axes to butt them together. During welding, the nozzle of the AM machining head 150 can simply emit a laser beam, or metal powder can be supplied to the boundary between the cutting strip and the dummy component D1 using a DED method. By welding the cutting strip Wa and the dummy component D1, a joint Wb is formed.

[0059] Figure 4DThe figure shows the state of the reprocessing step (ii) in which the metal product W1, to which the dummy component D1 is welded, is reprocessed while the metal product W1 is supported by the first support portion (first spindle 111) and the dummy component D1 is supported by the second support portion (second spindle 121). Supporting the metal product W1 at two points, the first spindle 111 and the second spindle 121, prevents vibration of the metal product W1 and improves reprocessing accuracy. In the reprocessing step of the metal product W1, machining such as milling is performed using the tool spindle 130 to form a reprocessed portion Wc. The reprocessing step can include either additional processing or a combination of removal and additional processing.

[0060] Figure 4E The figure shows the removal step (iii) of removing the dummy component D1 from the metal product W1 using the AM processing head 150 after the reprocessing step. However, the removal step can also be performed using the tool spindle 130, or both the tool spindle 130 and the AM processing head 150. When using the AM processing head 150 as shown in the example, the laser beam is emitted from the nozzle only and irradiated onto the bonded portion Wb, thereby melting the bonded portion Wb. Surface tension separates the molten metal into the metal product W1 side and the dummy component D1 side, physically separating the metal product W1 and the dummy component D1.

[0061] Figure 4F The figure shows the metal product W1 after the dummy component D1 has been removed. A residual portion Wd from the cutting tape Wa may remain on the circular edge of the second end portion of the metal product W1. This residual portion Wd can be removed using the tool spindle 130 or shaped to smooth the shape of the second end portion. If the residual portion Wd does not affect the function of the metal product W1, it can be left as is.

[0062] (Second embodiment)

[0063] Figure 5 A scenario showing another embodiment of the reprocessing method for a metal product W1 is shown. The metal product W1 has the same shape as that of the first embodiment. The first end of the metal product W1 is supported by the first spindle 111, which serves as the first support portion, as in the first embodiment. The dummy component D2 is disc-shaped and has a diameter larger than the circle formed by the circular edge, which serves as the second end of the metal product W1. A welded joint Wb is formed at the boundary between the circular edge, which serves as the second end of the metal product W1, and the dummy component D2. Here, the second end of the metal product W1 is supported by pushing the tailstock 170, which serves as the second support portion, against the center of one surface of the dummy component D2, which is connected to the second end. In this state, vibrations during the reprocessing step of machining the metal product W can also be suppressed.

[0064] (Third embodiment)

[0065] Figure 6 This embodiment illustrates a method for reprocessing a metal product W2 having a different shape from the metal product W1. The metal product W2 illustrated in the figure is a turbine blade, but the present invention is not limited to this embodiment. The first end of the metal product W2 is the root of the blade and is supported by the first spindle 111, which serves as the first support, as in the first embodiment. The dummy component D3 is cylindrical, with the X-axis as the center axis. The blade tip, which serves as the second end opposite the first end, is welded to a portion of the circumference of the cylindrical dummy component D3. A welded joint Wb is formed at the boundary between the blade tip, which serves as the second end of the metal product W2, and the dummy component D3. The second end of the metal product W2 is supported by a workpiece holder 180, which serves as the second support, pressing against the center of the lower surface (one cylindrical bottom surface) of the dummy component D3, which is connected to the second end. This configuration suppresses vibration during the reprocessing step of machining the metal product W2.

[0066] (Fourth embodiment)

[0067] Figure 7 A scenario showing another embodiment of the reprocessing method of the metal product W2 is shown. The metal product W2 has the same shape as the third embodiment. The first end of the metal product W2 is supported by the first spindle 111 as the first support portion, as in the first embodiment. The dummy component D4 is cylindrical with the Z-axis direction as the center axis. The second end of the metal product W2 is welded to the bottom surface of one side of the cylindrical dummy component D4, and a welded joint portion Wb is formed at the boundary between the second end of the metal product W2 and the dummy component D4. Here, the second end of the metal product W2 is supported by surrounding and sandwiching a portion of the circumference of the cylindrical dummy component D4 connected to the second end with a stabilizing bracket 190 as the second support portion. In this state, vibration can also be suppressed in the reprocessing step of machining the metal product W2.

[0068] Furthermore, when reworking asymmetric metal products, such as turbine blades, it is preferable to perform a process for adjusting the metal product's posture before the reworking process so that the largest principal surface of the virtual minimum rectangular parallelepiped containing the metal product forms an acute angle of 30° or less (preferably 10° or less) with the vertical direction. This allows for more precise machining of the metal product during the reworking process.

[0069] exist Figure 8The conceptual diagram in FIG. 2 shows an example of a turbine blade, a metal product W2, and a virtual minimum rectangular parallelepiped B housing it. One of the largest principal surfaces S of the virtual minimum rectangular parallelepiped B is shaded with diagonal lines. The metal product W2 is positioned so that the largest principal surface S forms the aforementioned acute angle with the vertical direction (i.e., the X-axis direction). It is most preferred that the largest principal surface S of the virtual minimum rectangular parallelepiped B forms an angle of 0° with the vertical direction (i.e., the two are parallel).

[0070] The description of the above embodiments is illustrative in all aspects and is not restrictive. Those skilled in the art will be able to make appropriate modifications and changes. The scope of the present invention is not represented by the above embodiments but by the claims. Furthermore, modifications of the embodiments within the scope of the claims are included within the scope of the present invention.

[0071] Industrial applicability

[0072] The present invention is suitable for reprocessing or repairing large metal products formed of expensive metal materials such as nickel-based alloys or titanium-based alloys.

[0073] Description of labels

[0074] 100: Machine tools

[0075] 110: 1st spindle station

[0076] 111: 1st main axis

[0077] 111a: First chuck mechanism

[0078] 120: Second spindle station

[0079] 121: Second main axis

[0080] 121a, b: Second chuck mechanism

[0081] 130: Tool spindle (1st tool station)

[0082] 140: 2nd tool station

[0083] 142: Rotating part

[0084] 150: AM processing head

[0085] 160: Bed

[0086] 170: Tailstock

[0087] 180: Workpiece support

[0088] 190: Stable bracket

[0089] 200: Processing space

[0090] 210: Cover (baffle)

[0091] 230: Cable

[0092] 300: Powder feeder

[0093] 310: Main box

[0094] 330: Buffer box

[0095] 340: Powder supply unit

[0096] 350: Inert gas supply unit

[0097] 400: Laser oscillator

[0098] W: workpiece

[0099] W1, W2: Metal products

[0100] Wa: Cutting tape

[0101] Wb: combined part

[0102] Wc: Reprocessing Department

[0103] Wd: residue

[0104] D, D1, D2, D3, D4: fake parts

Claims

1. A method for reprocessing a metal product, which is a method for reprocessing a metal product, characterized in that: have: Welding process, welding dummy parts onto the above metal products; a reworking step of reworking the metal product in a state where the metal product is supported by the first supporting portion and the dummy component is supported by the second supporting portion; as well as a removal step, after the reprocessing step, removing the dummy component from the metal product; The above welding process includes: cladding the cut strips onto the above metal products; as well as The dummy component is welded to the cut tape.

2. The metal product reprocessing method according to claim 1, characterized in that: The welding step and the reworking step are performed in a working space of a machine tool equipped with a welding torch for the welding step and a tool spindle for the reworking step.

3. The metal product reprocessing method according to claim 2, characterized in that: The above welding process includes: supporting the metal product by the first supporting portion in the processing space; supporting the dummy component by the second supporting portion in the processing space; and The metal product supported by the first supporting portion and the dummy member supported by the second supporting portion are welded.

4. The metal product reprocessing method according to claim 2 or 3, characterized in that: The above-mentioned machine tool has a compound lathe, One of the first support portion and the second support portion is a chuck mechanism provided on the spindle. The other of the first support portion and the second support portion is a workpiece support, a tailstock, a stabilizer support, or a chuck mechanism provided on a spindle different from the spindle.

5. The method for reprocessing a metal product according to any one of claims 1 to 3, wherein: The above-mentioned welding process is performed by metal lamination forming using the DED method.

6. The method for reprocessing a metal product according to any one of claims 1 to 3, wherein: Before the reprocessing step, the method further includes adjusting the posture of the metal product so that the largest main surface of the imaginary minimum rectangular parallelepiped containing the metal product forms an acute angle of 30° or less with the vertical direction.

7. The method for reprocessing a metal product according to any one of claims 1 to 3, wherein: The metal products mentioned above are rocket nozzles or turbine blades.

8. The method for reprocessing a metal product according to any one of claims 1 to 3, wherein: The metal product is formed of at least one selected from the group consisting of a titanium-based alloy, a cobalt-based alloy, and a nickel-based alloy.

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