JP2023039278A - Molded object manufacturing method and molded object - Google Patents

Abstract

To provide a molded object manufacturing method capable of easily forming a molded object having a cavity which has a smooth inner surface, and the molded object.SOLUTION: The molded object manufacturing method for forming a molded object W having a cavity 31 by layering a welded bead B having a filler material M fused and solidified comprises: a groove forming step of forming, on a base 40, a groove 35 which has a corner formed into a circular arc shape to become a part of the cavity 31; a cavity forming step of fitting a support member 37 in the groove 35 from an open side and sealing the groove 35 to form the cavity 31; and a fixing step of repeatedly forming the welded bead B so as to cover the outer surface of the support member 37, and fixing the support member 37 to the base 40.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method for manufacturing a modeled article and a modeled article.

In recent years, the need for 3D printers as a means of production has increased, and research and development are being carried out for practical application in the aircraft industry, etc., especially for application to metal materials. A 3D printer using a metal material melts metal powder or metal wire using a heat source such as a laser or an arc, and laminates the molten metal to form a modeled object.

In Patent Document 1, when forming a three-dimensional laminate model with a closed structure (hollow structure) that has a space inside by laminating beads with a torch, by repeating the steps of bead lamination and cutting, A build method is described that reduces build roughness on the sides of a build.

WO2017/163431

By the way, when forming a model having a cavity, it is desired that the inner surface of the cavity be smooth in order to reduce stress concentration.

According to the technique of Patent Literature 1, it is possible to suppress the roughness of the inner surface of the hollow portion to some extent, but it is difficult to form the inner surface of the hollow portion smoothly. In this case, it is conceivable to model the model while cutting the inner surface of the hollow portion with a cutting tool.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method for manufacturing a modeled article and a modeled article that can easily form a modeled article having a hollow portion with a smooth inner surface.

The present invention consists of the following configurations.
(1) A method for manufacturing a modeled article in which weld beads obtained by melting and solidifying a filler material are laminated to form a modeled article having a hollow portion,
a groove forming step of forming, in a base, a groove having arc-shaped corners and forming a part of the cavity;
a hollow portion forming step of forming the hollow portion by closing the groove portion by fitting a support member into the groove portion from the open side;
a fixing step of repeatedly forming the welding bead so as to cover the outer surface of the support member and fixing the support member to the base;
including,
A method of manufacturing a modeled object.
(2) A shaped article having a hollow portion in which weld beads obtained by melting and solidifying a filler material are laminated,
a base having an arc-shaped corner and a groove forming a part of the cavity;
a support member that is fitted from the open side of the groove to close the groove and form the cavity;
a shaping portion composed of the weld beads laminated so as to cover the outer surface of the support member;
with
sculpture.

ADVANTAGE OF THE INVENTION According to this invention, the model which has a cavity part with a smooth inner surface can be easily modeled.

1 is a schematic configuration diagram of a manufacturing system that manufactures a modeled object; FIG. FIG. 2 is a schematic cross-sectional view of a modeled article showing a structural example of the modeled article; 3A to 3D are schematic cross-sectional views of the modeled product in each step for explaining the method of manufacturing the modeled product. FIG. FIG. 11 is a schematic cross-sectional view of a molded article showing another example of the fixing process; FIG. 11 is a schematic cross-sectional view of a modeled object according to Modification 1; FIG. 11 is a schematic cross-sectional view of a modeled object according to Modification 2; FIG. 11 is a schematic cross-sectional view of a modeled object according to Modification 3;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a manufacturing system 100 for manufacturing a modeled object W of the present invention.

As shown in FIG. 1 , a model manufacturing system 100 having this configuration includes a welding robot 11 , a robot controller 13 , a filler material supply section 15 , a welding power source 19 , and a control section 21 .

The welding robot 11 is an actuator made up of an articulated robot, and a torch 23 is supported on the tip shaft. The position and posture of the torch 23 can be arbitrarily set three-dimensionally within the range of degrees of freedom of the robot arm. The torch 23 holds the linear filler material (welding wire) M continuously supplied from the filler material supply unit 15 in a state of protruding from the tip of the torch.

The torch 23 has a shield nozzle (not shown), and a shield gas is supplied to the welding portion from the shield nozzle. The arc welding method may be a consumable electrode type such as coated arc welding or carbon dioxide gas arc welding, or a non-consumable electrode type such as TIG welding or plasma arc welding, and is appropriately selected according to the object to be produced. .

For example, in the case of the consumable electrode type, a contact tip is arranged inside the shield nozzle, and the contact tip holds the filler material M to which the melting current is supplied. The torch 23 holds the filler material M and generates an arc from the tip of the filler material M in a shield gas atmosphere. The filler material M is fed to the torch 23 by a delivery mechanism (not shown) attached to a robot arm or the like. Then, when the continuously fed filler material M is melted and solidified while the torch 23 is moving, a welding bead B, which is a melted and solidified body of the filler material M, is formed.

The heat source for melting the filler material M is not limited to the arc described above. For example, a heat source using other methods such as a heating method using both an arc and a laser, a heating method using plasma, a heating method using an electron beam or a laser, or the like may be employed. When heating with an electron beam or laser, the amount of heating can be more finely controlled, the state of the welding bead B can be maintained more appropriately, and the quality of the modeled object W can be further improved.

The filler material M can be any commercially available welding wire. For example, MAG welding and MIG welding solid wire (JIS Z 3312) for mild steel, high strength steel and low temperature steel, arc welding flux cored wire (JIS Z 3312) for mild steel, high strength steel and low temperature steel 3313) or the like can be used.

An active metal such as titanium can also be used as the filler material M. In that case, it is necessary to create a shielding gas atmosphere in the weld zone in order to avoid oxidation and nitridation due to reaction with the atmosphere during welding.

The robot controller 13 receives instructions from the control section 21 to drive each section of the welding robot 11 and controls the output of the welding power source 19 as necessary.

The control unit 21 is composed of a computer device including a CPU, memory, storage, etc., and executes a drive program prepared in advance or a drive program created under desired conditions to drive each part such as the welding robot 11.

The manufacturing system 100 having the above configuration melts the filler material M while moving the torch 23 by driving the welding robot 11 along the movement trajectory of the torch 23 generated from the set layer shape data. A filler material M is supplied onto a base plate (base material) 41 . As a result, a modeled object W in which a plurality of linear welding beads B are laminated on the upper surface of the base plate 41 is formed.

Next, an example of the modeled object W manufactured in this example will be described.
FIG. 2 is a schematic cross-sectional view of the modeled object W showing a structural example of the modeled object W. As shown in FIG.

As shown in FIG. 2 , the modeled object W has a hollow portion 31 . The cavity 31 is used, for example, as a channel through which liquid or gas flows. The modeled object W includes a base 40 , a support member 37 and a modeled part 39 . A groove portion 35 is formed in the base 40 , and the hollow portion 31 is composed of the groove portion 35 and a support member 37 .

The base 40 is composed of a base plate (base material) 41 and a pair of wall portions 43 , and the wall portions 43 are formed on the upper surface of the base plate 41 . The wall portion 43 is composed of a plurality of welding beads B laminated on the base plate 41 and formed with a space therebetween.

A groove portion 35 formed in the base 40 is a concave portion surrounded by the base plate 41 and the wall portion 43 and constitutes a part of the hollow portion 31 . A weld bead Bs is fillet welded to the corner of the groove 35 . The groove portion 35 is formed by cutting the inner surface of the wall portion 43 and the welding bead Bs at the corner to be smooth, and the corner portion is formed in an arc shape.

The support member 37 is made of a metal material, and has a flat plate portion 45 and side plate portions 47. The side plate portions 47 are integrally formed on both side edges of the flat plate portion 45. As a result, the support member 37 is formed to have a concave cross section with one side open.

The support member 37 has a portion where the flat plate portion 45 and the side plate portion 47 are connected to each other and is curved in an arc shape. As a result, the inner surfaces of the corners of the flat plate portion 45 and the side plate portion 47 are formed in an arc shape. The support member 37 is fitted into the groove 35 with the open side facing the groove 35 . As a result, the groove portion 35 is closed by the support member 37 , and the hollow portion 31 is formed from the groove portion 35 and the support member 37 .

The shaped portion 39 is shaped by repeatedly forming the welding bead B. As shown in FIG. The shaped portion 39 is shaped to cover the surface of the support member 37 . Thereby, the support member 37 is fixed to the wall portion 43 . Of the welding beads B constituting the shaped portion 39, the welding beads Bb filled in the corners between the edge of the groove portion 35 and the side plate portion 47 of the support member 37 are welding beads for joining. The support member 37 is joined to the edge of the wall portion 43 forming the groove portion 35 by Bb. The joining point of the support member 37 to the edge of the groove 35 by the welding bead Bb for joining is aligned with the expected minimum principal stress caused by the bending force along the longitudinal direction of the cavity 31 .

Next, a method for manufacturing the modeled object W of the present invention will be described.
FIGS. 3A to 3D are schematic cross-sectional views of the modeled object W in each step for explaining the manufacturing method of the modeled object W. FIG.

(Groove forming step)
As shown in FIG. 3A, the welding robot 11 of the manufacturing system 100 is driven to move the torch 23 and deposit the welding bead B on the upper surface of the base plate 41 . As a result, the base plate 41 and the pair of wall portions 43 form a groove portion 35 having a concave cross section in the base 40 . Further, a welding bead Bs is fillet-welded to the corner of the groove 35 . In addition, the inner surfaces of the walls 43 and the corners of the formed groove 35 are formed smooth by cutting.

(Cavity forming step)
As shown in FIG. 3B, the support member 37 is fitted into the groove 35 formed in the base 40 with the open side facing the groove 35 . By doing so, the groove 35 is closed by the support member 37 having a concave cross section, and the cavity 31 is formed.

(fixing process)
As shown in FIG. 3C, the welding robot 11 of the manufacturing system 100 is driven to move the torch 23, and the welding bead B is laminated so as to cover the outer surface of the support member 37. As shown in FIG. Thereby, the support member 37 is fixed to the wall portion 43 forming the groove portion 35 . Then, as shown in FIG. 3D, a modeled portion 39 is formed on the support member 37 and the wall portion 43 . As a result, the modeled object W having the hollow portion 31 is obtained.

Here, of the welding beads B formed so as to cover the outer surface of the support member 37, the welding beads B filled in the corners of the edge portion of the groove portion 35 and the side plate portion 47 of the support member 37 are welding beads Bb for joining. It is said that The support member 37 is joined to the edge of the groove portion 35 by the welding bead Bb. It is preferable that the joining point of the support member 37 to the edge portion of the groove portion 35 by the welding bead Bb for joining is aligned with the expected minimum principal stress caused by the bending force along the longitudinal direction of the hollow portion 31 .

As shown in FIG. 4, the edges of the groove 35 are cut so that the gap between the edge of the groove 35 and the outer surface of the support member 37 becomes large when the support member 37 is fitted into the groove 35 . is preferably cut obliquely. In this way, when the support member 37 is joined to the edge of the groove portion 35 by the welding beads Bb for joining, more welding beads Bb can be filled to increase the joining force.

As described above, according to the manufacturing method of the modeled object W and the modeled object W according to the present configuration, the hollow portion 31 is formed by fitting the support member 37 into the groove portion 35 having the arc-shaped corners. After that, a welding bead B is repeatedly formed so as to cover the outer surface of the support member 37 to fix the support member 37 to the base 40 . As a result, it is possible to manufacture the modeled object W having the hollow portion 31 with a smooth inner surface shape.

In addition, since the ceiling portion of the hollow portion 31 is formed by the support member 37, the hollow portion 31 can be smoothly formed while suppressing burn-through of the welding bead B as compared with the case where the ceiling portion is formed by the welding bead B. .

In addition, it is possible to manufacture a modeled object W with excellent load resistance in which the strength of the hollow portion 31 is increased by the support member 37 .

Moreover, by using the support member 37 having a concave cross section with arc-shaped corners, it is possible to easily form the cavity 31 with four arc-shaped corners and suppressed stress concentration.

In addition, if the inner surface and corners of the groove 35 are smoothed by cutting before the support member 37 is fitted into the groove 35 to close the groove 35, the shaped object W having the cavity 31 with a smoother inner surface shape can be manufactured. be able to.

Also, the support member 37 is joined to the edge of the groove 35 at the expected minimum principal stress generated by the bending force along the longitudinal direction of the cavity 31 . As a result, when a bending force is applied along the longitudinal direction of the hollow portion 31 after molding and a principal stress is generated, the effect of the principal stress on the joining portion between the support member 37 and the edge portion of the groove portion 35 can be suppressed. can.

Next, each modified example will be described.
(Modification 1)
FIG. 5 is a schematic cross-sectional view of a modeled object W according to Modification 1. As shown in FIG.

As shown in FIG. 5, in Modification 1, the corners of the flat plate portion 45 and the side plate portion 47 are formed in an arc shape, and the edge portion of the side plate portion 47 is curved inward to form an arc shape. A support member 37 is used. In Modification 1, by fitting the support member 37 into the groove portion 35, the edge portion of the side plate portion 47 formed in an arc shape fits into the corner portion of the groove portion 35 fillet-welded by the welding bead Bs. Butted.

According to this modified example 1, since the support member 37 has arcuate corners between the flat plate portion 45 and the side plate portion 47 and the edge portion of the side plate portion 47, the stress concentration at the four corners is suppressed. The portion 31 can be easily formed.

(Modification 2)
FIG. 6 is a schematic cross-sectional view of a modeled object W according to Modification 2. As shown in FIG.

As shown in FIG. 6, in Modification 2, a tubular support member 37 having a rectangular cross-section and four arc-shaped corners is used. In Modification 2, by fitting the support member 37 into the groove 35, the front corner in the fitting direction abuts against the corner of the groove 35 fillet-welded by the welding bead Bs.

According to Modification 2, by mechanically fitting the cylindrical support member 37 into the groove 35, the cavity 31 having a smooth inner surface can be easily formed. Further, by using the tubular support member 37 having a rectangular cross section with four arc-shaped corners, it is possible to easily form the cavity 31 with four arc-shaped corners and suppressed stress concentration. .

(Modification 3)
FIG. 7 is a schematic cross-sectional view of a modeled object W according to Modification 3. As shown in FIG.

As shown in FIG. 7, in Modification 3, the groove portion 35 is formed by cutting the base plate 41 . A hollow portion 31 is formed by fitting a support member 37 into the groove portion 35 of the base 40 composed of the base plate 41 having the groove portion 35 .

According to Modification 3, since the hollow portion 31 is formed by fitting the support member 37 into the cut groove portion 35 of the base plate 41, the hollow portion 31 having a smooth inner surface can be easily formed. Further, the groove portion 35 can be precisely formed by cutting, and the support member 37 can be fitted into the groove portion 35 with high accuracy.

As described above, the present invention is not limited to the above-described embodiments, and those skilled in the art can make modifications and applications by combining each configuration of the embodiments with each other, based on the description of the specification and well-known techniques. It is also contemplated by the present invention that it falls within the scope of protection sought.

As described above, this specification discloses the following matters.
(1) A method for manufacturing a modeled product in which weld beads obtained by melting and solidifying a filler material are laminated to form a modeled product having a hollow portion,
a groove forming step of forming, in a base, a groove having arc-shaped corners and forming a part of the cavity;
a hollow portion forming step of forming the hollow portion by closing the groove portion by fitting a support member into the groove portion from the open side;
a fixing step of repeatedly forming the welding bead so as to cover the outer surface of the support member and fixing the support member to the base;
A method of manufacturing a modeled object, comprising:
According to the manufacturing method of the shaped article having this configuration, the support member is fitted into the groove having the arc-shaped corner to form the hollow portion, and then the welding bead is repeatedly formed so as to cover the outer surface of the support member. forming to secure the support member to the base; As a result, it is possible to manufacture a modeled object having a hollow portion with a smooth inner surface shape.
In addition, since a part of the cavity, such as the ceiling portion, is formed by the support member, the cavity can be formed smoothly while suppressing burn-through of the welding bead compared to the case where the ceiling portion is formed by the welding bead.
In addition, it is possible to manufacture a modeled object with excellent load resistance in which the strength of the hollow portion is increased by the support member.

(2) In the step of forming the hollow portion, the support member having a concave cross-section in which the side plate portions are continuously provided on both side edges of the flat plate portion and the corners between the flat plate portion and the side plate portions are formed in an arc shape is opened. The method for manufacturing a modeled article according to (1), wherein the molded article is fitted into the groove with the side facing the groove.
According to the manufacturing method of the shaped article having this configuration, by mechanically fitting the support member having a concave cross-section into the groove with the open side facing the groove, it is possible to easily form a cavity having a smooth inner surface shape. . In addition, by using a support member having a concave cross-sectional shape with arc-shaped corners, it is possible to easily form a cavity with four arc-shaped corners and suppressed stress concentration.

(3) The method of manufacturing a model according to (2), wherein the support member has an arcuate edge portion of the side plate portion.
According to the manufacturing method of the shaped object having this configuration, since the edge portions of the side plate portions of the support member are formed in an arc shape, it is possible to easily form the hollow portions in which the stress concentration at the four corners is suppressed.

(4) The method of manufacturing a model according to (1), wherein in the cavity forming step, the cylindrical support member having a rectangular cross-section and four arc-shaped corners is fitted into the groove.
According to the method for manufacturing a modeled object having this configuration, it is possible to easily form a cavity having a smooth inner surface shape by mechanically fitting the cylindrical support member into the groove. In addition, by using a cylindrical support member having a rectangular cross-section with four arc-shaped corners, it is possible to easily form a hollow portion with four arc-shaped corners and suppressed stress concentration.

(5) In the groove forming step,
forming walls constituting both sides of the groove by laminating the welding bead on the base material;
forming the welding bead at a corner of the wall portion with the base;
The method for manufacturing a model according to any one of (1) to (4), wherein the inner surfaces of the wall portion and the corner portion are machined.
According to the manufacturing method of the model having this configuration, the inner surface and the corners of the groove are cut and smoothed before the support member is fitted into the groove to close it, thereby forming a cavity with a smoother inner surface shape. It is possible to manufacture a modeled object that has

(6) The method of manufacturing a shaped article according to any one of (1) to (4), wherein in the groove forming step, the base material is cut to form the groove.
According to the manufacturing method of the model having this configuration, since the cavity is formed by fitting the support member into the cut groove, it is possible to easily form the cavity having a smooth inner surface shape. Further, the groove can be precisely formed by cutting, and the support member can be fitted into the groove with high accuracy.

(7) The support member according to any one of (1) to (6), wherein the support member is joined to the edge of the groove at the expected minimum principal stress point caused by the bending force along the longitudinal direction of the cavity. The manufacturing method of the molding.
According to the manufacturing method of the model having this configuration, the support member is joined to the edge of the groove at the expected minimum principal stress caused by the bending force along the longitudinal direction of the cavity. As a result, when a bending force is applied along the longitudinal direction of the hollow portion after molding and a principal stress is generated, the effect of the principal stress on the joining portion between the support member and the edge portion of the groove can be suppressed.

(8) Cutting the edge of the groove on the open side and filling the gap between the edge of the groove and the outer surface of the support member with welding beads for bonding to join the support member; (7) The method for manufacturing a modeled article according to any one of (7).
According to the manufacturing method of the model having this configuration, the support member can be firmly joined by filling the gap between the cut edge of the groove and the outer surface of the support member with the welding bead for joining.

(9) A shaped article having a cavity in which welding beads obtained by melting and solidifying a filler material are laminated,
a base having an arc-shaped corner and a groove forming a part of the cavity;
a support member that is fitted from the open side of the groove to close the groove and form the cavity;
a shaping portion composed of the weld beads laminated so as to cover the outer surface of the support member;
Sculpted object with
According to the modeled product of this configuration, the supporting member is fitted into the groove having the arc-shaped corner to form the hollow portion, and the welding bead is laminated so as to cover the outer surface of the supporting member to form the modeled portion. molded. As a result, it is possible to obtain a modeled object having a hollow portion with a smooth inner surface shape.
In addition, it is possible to obtain a modeled product with excellent load resistance in which the strength of the hollow portion is increased by the support member.

(10) The support member has a concave cross-sectional shape in which side plate portions are continuously provided on both side edges of a flat plate portion and corners between the flat plate portion and the side plate portions are formed in an arc shape, and the open side of the support member The modeled article according to (9), wherein the hollow portion is formed by fitting into the groove portion toward the groove portion.
According to the shaped article having this configuration, the support member having a concave cross-section is fitted into the groove with the open side facing the groove to form a cavity having a smooth inner surface. In addition, since the support member has a concave cross-sectional shape with arc-shaped corners, it is possible to obtain a shaped article having cavities in which stress concentration at the four corners is suppressed.

(11) The modeled article according to (10), wherein the supporting member has an arcuate edge portion of the side plate portion.
According to the shaped article having this configuration, since the edge portions of the side plate portions are formed in a circular arc shape, the shaped article having the hollow portions in which stress concentration at the four corners is suppressed can be obtained.

(12) The modeled object according to (9), wherein the tubular support member having a rectangular cross-section and four arc-shaped corners is fitted in the groove.
According to the modeled product having this configuration, the cylindrical support member having a rectangular cross section is fitted into the groove to form a cavity having a smooth inner surface. In addition, since the support member has four arc-shaped corners, it is possible to obtain a molded article having a hollow portion in which stress concentration at the four corners is suppressed.

(13) A welding bead for joining is filled between the support member and the edge of the groove,
The shaped article according to any one of (9) to (12), wherein the support member is joined to the edge of the groove by the welding bead for joining.
According to the shaped article having this configuration, the support member is firmly joined to the edge of the groove by the welding bead for joining filled between the edge of the groove and the outer surface of the support member.

(14) The shaped article of (13), wherein the support member is joined to the edge of the groove at a point of least expected principal stress caused by a bending force along the length of the cavity.
According to the modeled article of this configuration, the support member is joined to the edge of the groove at the expected minimum principal stress caused by the bending force along the longitudinal direction of the cavity. Thereby, when a bending force is applied along the longitudinal direction of the hollow portion and a principal stress is generated, the effect of the principal stress on the joining portion between the support member and the edge portion of the groove can be suppressed.

31 Cavity 35 Groove 37 Support member 40 Base 41 Base plate (base material)
43 wall portion 45 flat plate portion 47 side plate portion B, Bb, Bs welding bead M filler material W modeled object

Claims (14)

A method for manufacturing a modeled article by laminating welding beads obtained by melting and solidifying a filler material to form a modeled article having a cavity,
a groove forming step of forming, in a base, a groove having arc-shaped corners and forming a part of the cavity;
a hollow portion forming step of forming the hollow portion by closing the groove portion by fitting a support member into the groove portion from the open side;
a fixing step of repeatedly forming the welding bead so as to cover the outer surface of the support member and fixing the support member to the base;
including,
A method of manufacturing a modeled object. In the hollow portion forming step, the support member having a concave cross-section in which the side plate portions are continuously provided on both side edges of the flat plate portion, and the corners between the flat plate portion and the side plate portions are formed in an arc shape, the open side is set to the above-described shape. fitting into the groove toward the groove;
The manufacturing method of the modeled article according to claim 1 . In the support member, the edge of the side plate portion is formed in an arc shape,
3. The method of manufacturing a modeled article according to claim 2. In the hollow portion forming step, the cylindrical support member having a rectangular cross-section and having four arc-shaped corners is fitted into the groove;
The manufacturing method of the modeled article according to claim 1 . In the groove forming step,
forming walls constituting both sides of the groove by laminating the welding bead on the base material;
forming the welding bead at a corner of the wall portion with the base;
cutting the inner surface of the wall and the corner;
A method for manufacturing a shaped article according to any one of claims 1 to 4. In the groove forming step, the base material is cut to form the groove,
A method for manufacturing a shaped article according to any one of claims 1 to 4. bonding the support member to the edge of the groove at the expected minimum principal stress caused by bending forces along the length of the cavity;
A method for manufacturing a shaped article according to any one of claims 1 to 6. Cutting the edge of the groove on the open side, filling the gap between the edge of the groove and the outer surface of the support member with a welding bead for bonding to join the support member;
A method for manufacturing a shaped article according to any one of claims 1 to 7. A shaped article having a cavity in which weld beads obtained by melting and solidifying a filler material are stacked,
a base having an arc-shaped corner and a groove forming a part of the cavity;
a support member that is fitted from the open side of the groove to close the groove and form the cavity;
a shaping portion composed of the weld beads laminated so as to cover the outer surface of the support member;
with
sculpture. The supporting member has a concave cross-sectional shape in which side plate portions are continuously provided on both side edges of a flat plate portion, and corners between the flat plate portion and the side plate portions are formed in an arc shape, and an open side of the support member faces the groove portion. The hollow portion is configured by being fitted into the groove portion by
The shaped article according to claim 9 . In the support member, the edge of the side plate portion is formed in an arc shape,
The shaped article according to claim 10 . The cylindrical support member having a rectangular cross-section with four arc-shaped corners is fitted in the groove,
The shaped article according to claim 9 . A welding bead for joining is filled between the support member and the edge of the groove,
The support member is joined to the edge of the groove by the welding bead for joining,
The shaped article according to any one of claims 9 to 12. the support member is joined to the edge of the groove at a point of least expected principal stress caused by a bending force along the length of the cavity;
14. The shaped article according to claim 13.

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