JP2009190043A - Structural member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structural member which can be manufactured by press forming and achieves improvement of strength. <P>SOLUTION: In the structural member 1 formed by bending a pipe material 2 through press forming, a core metal member 4 supporting inner wall surfaces at the inner and outer sides of bending at a bending part 3 is inserted into the bending part 3 of the pipe material 2 to prevent the buckling and dropping of the bending part 3, and the pipe material 2 is bent. The core metal member 4 and the bending part 3 are integrally deformed together and the deformed core metal member 4 is made to be the reinforcement member of the bending part 3 after the bending. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a structural member formed by bending a pipe material by press molding.

  Conventionally, as a structural member used for a pillar of a cab for a construction machine, there is one formed by bending a pipe (hollow cross-section material) such as a steel pipe.

  As a method for manufacturing such a structural member, for example, Patent Document 1 proposes bending a steel pipe with a roll bender (pipe bender).

  In the pipe bender, a plurality of rolls are arranged based on a bending span and a bending radius, and the pipe is passed between the rolls to be bent.

  Furthermore, in patent document 1, when bending a pipe, in order to prevent the deformation | transformation and buckling in the vicinity of the bending part of a pipe, a core material (core metal) is put in a pipe, it bends, and after a bending process, a core metal Is removed from the pipe.

JP-A-8-252636

  However, in the above-mentioned pipe bender, since it is necessary to pull out the metal core from the pipe after bending, man-hours are required for the drawing. Since the core metal is worn by bending, it has caused variations in the processing accuracy of the pipe and shortened the life of the core metal.

  In addition, the bending by the pipe bender has problems such as a long processing time and a large molding force.

  Therefore, as shown in FIG. 14, it is conceivable that the bending process of the pipe 141 is performed by press molding. However, since the press molding presses only the bending part 143 of the pipe 141 with the punch 142, The stress is likely to concentrate, and there is a possibility that the bending portion 143 may be contracted (see symbol S) or buckled (see symbol B).

  When such shrinkage or buckling occurs, there is a problem that the strength of the structural member near the bent portion 143 is insufficient.

  Accordingly, an object of the present invention is to provide a structural member that solves the above-described problems and can be manufactured by press molding and has improved strength.

  In order to achieve the above object, according to the present invention, in a structural member formed by bending a pipe material by press molding, the bent portion is buckled and retracted in a bent portion where the pipe material is bent. In order to prevent this, the metal core member that supports the inner wall surfaces on the inner side and the outer side of the bent portion is inserted to bend the pipe material, and the core metal member is deformed integrally with the bent portion. The deformed cored bar member is used as a strength member for the bent portion after the bending process.

  Preferably, the metal core member includes a core portion formed by arranging a plurality of plate materials having the same shape as a cross-sectional shape of the bent portion along the axial direction of the pipe material, and the plate material of the core portion is the above-described plate material. It has a connection part which changes with an above-mentioned bending process while connecting with an axial direction.

  Preferably, in the cored bar member, the axial length of the core part is the same as the length of the bent part.

  Preferably, the core part of the cored bar member is welded to the inner wall of the bent part after the bending process.

  Preferably, the front pillar portion and the roof rail portion are formed integrally with a cab of a construction machine.

  According to the present invention, it is possible to produce an excellent effect that a structural member can be manufactured from a pipe material by press molding and the strength of the structural member can be improved.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  The structural member of this embodiment is applied to, for example, a cab of a construction machine such as a power shovel or a dump truck.

  First, a schematic structure of a cab of a construction machine will be described based on FIG.

  As shown in FIG. 6, a front portion of the cab 61 is provided with a pair of front pillar portions 62 that are spaced apart from each other and extend vertically. A front window 63 that covers the front surface of the cab 61 is interposed between the front pillar portions 62. Is provided. The front pillar portion 62 in the figure is inclined backward as it goes from the lower end to the upper end.

  A rear part of the cab 61 is provided with a pair of rear pillars 64 that are separated from each other in the left-right direction and extend vertically. The upper end portion of the rear pillar portion 64 and the upper end portion of the front pillar portion 62 are connected by a pair of left and right roof rail portions 65 extending in the front-rear direction, and a roof panel 67 that covers the ceiling surface of the cab 61 is provided between the roof rail portions 65. It is done.

  An upper end portion of the front pillar portion 62 is connected by a front header portion 68 extending in the left-right direction, and an upper end portion of the rear pillar portion 64 is connected by a rear header portion 69 extending in the left-right direction. The lower end portion of the front pillar portion 62 is connected by a front cross member portion 70 extending in the left-right direction, and the lower end portion of the rear pillar portion 64 is connected by a rear cross member portion 71 extending in the left-right direction. The lower end portion of the front pillar portion 62 and the lower end portion of the rear pillar portion 64 are connected by a side member portion 72 that extends in the front-rear direction.

  In the illustrated cab 61, the front pillar portion 62 and the roof rail portion 65 have a closed cross-sectional shape and are integrally formed. That is, the front pillar portion 62 and the roof rail portion 65 are formed of one hollow structural member that is continuous without a joint portion by welding or the like. The integrated front pillar portion 62 and roof rail portion 65 are formed by the structural member 1 of the present embodiment.

  The structural member of this embodiment is demonstrated based on FIGS. 1-4.

  The structural member 1 of the present embodiment is a cab (canopy) structural member 1 and includes a pipe material 2 that is bent and a cored bar member 4 that is inserted into a bent portion 3 of the pipe material 2.

  Specifically, as shown in FIG. 1, the structural member 1 is formed by bending a pipe material 2 by press molding, and is placed in a bent portion 3 where the pipe material 2 is bent. In order to prevent the bending portion 3 from buckling and contracting, the core metal member 4 that supports the inner wall surface 31 (see FIG. 3) inside the bending portion and the inner wall surface 32 outside the bending portion 3 is inserted. 2, the cored bar member 4 is deformed integrally with the bent part 3, and the deformed cored bar member 4 is used as a strength member of the bent part 3 after the bending process.

  As shown in FIG. 2, the pipe material 2a before bending (hereinafter referred to as blank pipe material) 2a has a rectangular (substantially square) cross-sectional shape and extends substantially linearly. The blank pipe material 2a is formed from, for example, a steel pipe.

  The blank pipe material 2a is formed into a substantially “<” shape (or L shape) by bending. Hereinafter, the pipe material 2 after bending is referred to as a post-processing pipe material 2.

  The bending portion 3 is provided at the center in the longitudinal direction of the blank pipe material 2a (and the processed pipe material 2). In the pipe material 2 after processing, the bending portion 3 is composed of a portion from the R stop (boundary between the straight portion and the curved portion) to the R stop.

  The processed pipe material 2 is bent so as to protrude downward, and in FIGS. 1 and 2, the upper side is the inner side of the bending, and the lower side is the outer side of the bending.

  The core metal member 4 includes a core portion 6 formed by arranging a plurality of plate materials 5 (plates) having the same shape as the cross-sectional shape of the bent portion 3 (blank pipe material 2a) along the axial direction of the blank pipe material 2a; The plate member 5 of the core portion 6 is connected in the axial direction and has a connecting pin 7 that forms a connecting portion that is deformed by bending.

  As shown in FIG. 3, the core portion 6 has an axial length that is substantially the same as that of the bending portion 3 before bending, and a plurality of plate members 5 are stacked in the axial direction with no gaps (stacked). )It is formed. Specifically, the number of plate members 5 and / or the plate thickness of the core portion 6 is set so that the axial length is substantially the same as that of the bent portion 3 before bending. Although details will be described later, the core portion 6 has a length in the axial direction that is the same as that of the bending portion 3 even after the bending process by being deformed into a fan shape during the bending process. The core portion 6 may be formed longer than the bending portion 3 in order to provide a margin for bending.

  Each plate member 5 of the core portion 6 has an outer shape substantially similar to the shape of the hollow portion of the blank pipe material 2a, and is formed slightly smaller than the hollow portion so as to be inserted into the blank pipe material 2a. . The plate material 5 of this embodiment is formed from the same material (steel material etc.) as the blank pipe material 2a, for example.

  As shown in FIG. 4, a coupling hole 8 (round hole in the figure) through which the coupling pin 7 is inserted is formed in the plate material 5. The coupling hole 8 penetrates the plate 5 in the axial direction and is formed eccentrically inside the bending R of the cored bar member 4 (bending portion 3).

  That is, the coupling hole 8 is formed so as to be eccentric (offset) from the center of the plate member 5 (the axial center of the pipe member 2) when the core portion 6 is accommodated in the bent portion 3 to the inside of the bend. In FIG. 4, the coupling hole 8 is formed at a position offset upward from the center of the square.

  The coupling pin 7 has an outer diameter slightly smaller than the inner diameter of the coupling hole 8 of the plate member 5. The gap between the coupling pin 7 and the coupling hole 8 is set smaller than the gap between the plate material 5 and the pipe material 2. The coupling pin 7 is made of, for example, a round bar made of the same material as the blank pipe material 2a.

  The coupling pin 7 extends in the axial direction through the core portion 6, and both end portions protrude from the core portion 6. At both ends of the coupling pin 7, flanges 9 for holding the plate material 5 of the core part 6 are provided.

  The flange portion 9 has an outer diameter larger than the coupling hole 8 of the plate material 5, holds the plate material 5 integrally from both sides in the axial direction, and restricts the movement of the plate material 5 in the axial direction. The flange portion 9 is formed in a disk shape, for example, and is welded to both end portions of the coupling pin 7.

  In the present embodiment, the outer periphery of the plate member 5 of the core portion 6 is welded after bending, so that the inner wall surfaces of the bending portion 3 (in the illustrated example, the inner wall surfaces 31 and 32 on the inner and outer sides of the bend and the inner and outer surfaces thereof). It is welded and joined to other inner wall surfaces 33, 34) connecting the inner wall surfaces 31, 32.

  Next, an example of a press used to form the structural member 1 of the present embodiment will be described based on FIG.

  As shown in FIG. 5, the press machine 51 includes a punch 52 (upper mold) that can be moved up and down, and a die 53 (lower mold) that is provided below the punch 52 and holds the blank pipe material 2a. Prepare.

  The dice 53 hold | maintains the part of the axial direction outer side of the bending part 3 of the blank pipe material 2a, respectively. In the illustrated example, two dice 53 are arranged apart from each other on the left and right. A holding groove 54 is formed on the upper surface of each die 53 to hold the blank pipe material 2a from below. The die may be a single die extending along the axial direction of the blank pipe material 2a.

  The punch 52 is located above the bent portion 3 of the blank pipe material 2a, and has a length (length in the left-right direction in FIG. 5) that is substantially the same as the axial length of the bent portion 3.

  At the tip (lower end) of the punch 52, the bent portion 3 of the recessed blank pipe material 2a is fitted upward, and a concave portion 55 for pressing the bent portion 3 downward is formed. The concave portion 55 forms a molding surface and is formed in a shape corresponding to the product shape (bending radius or the like) of the bending portion 3. For example, the upper surface of the recess 55 is formed in a mountain shape that protrudes downward.

  Next, the manufacturing method of the structural member 1 of this embodiment is demonstrated based on FIG. 1 and FIG.

  In this embodiment, as shown in FIG. 2, first, the metal core member 4 is set in the bent portion 3 of the straight tubular blank pipe material 2a. Specifically, the cored bar member 4 is inserted from one end of the blank pipe material 2a, and the inserted cored bar member 4 is moved to the axially central side to the bent part 3 to be arranged and positioned in the bent part 3. To do.

  Here, the cored bar member 4 is inserted by aligning the direction of the cored bar member 4 so that the coupling pin 7 is positioned inside the bend. The cored bar member 4 is moved by engaging a jig such as a wire or a rod with the cored bar member 4 and pushing or pulling the cored bar member 4 through the jig. The arrangement and positioning of the cored bar member 4 are performed so that the axial center of the core part 6 coincides with the axial center of the bending part 3.

  Next, as shown in FIG. 1, the blank pipe material 2a in which the cored bar member 4 is inserted is press-molded by the press machine 51 of FIG.

  Specifically, the punch 52 is lowered and the bending portion 3 is pressed downward to bend, and the cored bar member 4 in the bending portion 3 is deformed integrally with the bending portion 3 into a fan shape.

  Thereby, the bending part 3 is curving in the shape of "<" as a whole, while a bending inner side shrinks and a bending outer side expands. In the cored bar member 4, the coupling pin 7 is curved along the bent portion 3, and the gap between the adjacent plate material 5 of the core portion 6 and the adjacent plate material 5 increases from the inner side to the outer side of the bend. Separated from each other.

  During this bending process, the cored bar member 4 suppresses and prevents buckling of the inner wall surface 31 on the inner side of the bending portion 3 and shrinkage of the inner wall surface 32 on the outer side of the bending.

  That is, a compressive force is applied to the inner wall surface 31 (see FIG. 3) inside the bending when the bending portion 3 is processed, but the inner wall surface 31 inside the bending is supported by the plate material 5 of the cored bar member 4 in this embodiment. Therefore, the deformation | transformation to a bending outer side (refer FIG. 7 code | symbol B) is suppressed, and buckling is prevented. In addition, a tensile force is applied to the inner wall surface 32 on the outer side of the bending portion 3, but in this embodiment, since the core metal member 4 is supported by the plate material 5, deformation to the inner side of the bending (see S in FIG. 7). Suppressed and closed.

  Furthermore, the cored bar member 4 of the present embodiment is deformed in a direction in which the space between the plate members 5 on the outer side of the bend is opened and the space between the plate members 5 on the inner side of the bend is closed. ) Is tightened and fixed by the strain caused by the expansion and contraction of the pipe material 2. The fixed metal core member 4 serves as a strength member for increasing the strength of the bent portion 3.

  In this embodiment, after the bending process, the cored bar member 4 is joined in the bent part 3 in order to fix the cored bar member 4 (strength member) more firmly.

  The core metal member 4 is joined by welding the plate member 5 of the core portion 6 of the core metal member 4 to the inner wall surface of the bent portion 3 by welding. As a welding method, for example, laser welding in which a laser is irradiated from the surface side of the processed pipe material 2 or plug welding in which a through hole is formed in the processed pipe material 2 can be considered.

  The structural member 1 of this embodiment is obtained by the above.

  Thus, in this embodiment, the rigidity of the structural member 1 can be improved by fixing the cored bar member 4 in the bending part 3 and making it a strength member.

  That is, in the structural member 1 of the present embodiment, each plate member 5 of the cored bar member 4 fixed in the bent portion 3 becomes a partition wall that partitions the interior of the pipe material 2 after processing into the structural member 1. A node is formed, and the rigidity of the structural member 1 (particularly, near the bent portion 3) is increased.

  Further, by welding the bent portion 3 of the pipe material 2 after processing and the cored bar member 4, the bonding strength between the bent part 3 and the cored bar member 4 is increased, and the cored bar member 4 is dropped from the pipe material 2 after processing. In addition to preventing this, the rigidity of the structural member 1 can also be improved.

  In addition, the bending member 3 is supported by the cored bar member 4 during the bending process to prevent deformation (drag) and buckling, thereby enabling the production of the structural member 1 by the press machine 51, and the pipe bender. do not need.

  The bending process by the pipe bender requires a large pipe bender because a large processing torque is required because the rotation center of the bending process and the part to be processed (blank pipe material 2a) are separated from each other. Accordingly, processing with a small general-purpose press 51 is possible.

  Further, in bending by a pipe bender, investment such as a former, a mandrel, and a guide is necessary. However, in this embodiment, only a punch 52 that presses the vicinity of the bending portion 3 and a die 53 that supports the blank pipe material 2a. As a result, the mold cost can be reduced and investment can be reduced compared to pipe vendors.

  Next, another embodiment will be described based on FIG.

  In the present embodiment, the shape of the core part of the cored bar member is different from that of the embodiment of FIG. 1 described above, and the other parts are the same as those of the embodiment of FIG. Therefore, the same elements as those in the embodiment of FIG. 1 are designated by the same reference numerals in the drawing, and detailed description thereof is omitted.

  As shown in FIG. 7, the core portion 71 of the present embodiment is such that the plate members at both ends of the plurality of plate members 5 arranged along the axial direction of the pipe member 2 are thicker than the other plate members 5. The large thick plate 72 is formed.

  The thick plates 72 are located at both ends of the bending portion 3, and the outer periphery of the thick plate 72 is bonded to the inner wall surface of the pipe material 2 by welding after bending.

  In the present embodiment, the same effect as that of the embodiment of FIG. 1 described above is obtained, and furthermore, nodes having high strength due to the thick plates 72 are formed at both ends of the bending portion 3, so that the embodiment of FIG. The rigidity of the structural member 1 (bending part 3) can be improved.

  Next, another embodiment will be described based on FIGS. 8 and 9.

  In the present embodiment, a jig for positioning the cored bar member 4 at the bent portion is different from the embodiment of FIG. 1 described above, and the other parts are the same as those of the embodiment of FIG. Therefore, the same elements as those in the embodiment of FIG. 1 are designated by the same reference numerals in the drawing, and detailed description thereof is omitted.

  As shown in FIGS. 8 and 9, the jig 81 of the present embodiment includes a guide pin 82 that extends along the axial direction of the blank pipe material 2 a and can be inserted into the blank pipe material 2 a, and the tip of the guide pin 82. And a flange 83 that can be engaged with the core portion 6 and a stopper 84 that is provided at the base end portion of the guide pin 82 and that can engage with one end of the blank pipe member 2a. Further, each plate member 5 of the core portion 6 of the present embodiment is formed with a guide hole 85 (for example, a round hole) through which the tip portion of the guide pin 82 passes.

  The flange 83 is made of, for example, a disk having a diameter larger than that of the guide hole 85 of the plate material 5, and the stopper 84 is formed larger than the cross section of the blank pipe material 2 a, and has a shape similar to the cross section of the blank pipe material 2 a, for example. It consists of a plate.

  The flange 83 and the stopper 84 are joined to the guide pin 82 by welding or the like, and are arranged at a predetermined interval in the axial direction. Specifically, the flange 83 and the stopper 84 are arranged on the guide pin 82 so that the length L from the flange 83 to the stopper 84 matches the length from the bent portion 3 to one end of the blank pipe material 2a. Is done.

  In this embodiment, the gap between the guide pin 82 and the guide hole 85 and the gap between the coupling pin 7 and the coupling hole 8 are larger than the gap between the inner wall surface of the pipe material 2 and the plate material 5 of the core portion 6. Set small.

  Next, the setting and positioning of the cored bar member 4 in the blank pipe material 2a will be described.

  First, the metal core member 4 is inserted from one end (the left end in FIG. 8) of the blank pipe member 2a, and the guide pin 82 is inserted from the front end into the guide hole 85 of the plate material 5 of the metal core member 4 so that the flange 83 is formed. It abuts on the plate material 5.

  Next, the guide pin 82 is fed into the blank pipe material 2 a, and the cored bar member 4 is moved from one end of the blank pipe material 2 a toward the bending portion 3 through a flange 83 fixed to the guide pin 82. Further, the guide pin 82 is fed until the stopper 84 comes into contact with one end of the blank pipe material 2a. As a result, the cored bar member 4 reaches the bent portion 3 and is positioned at a predetermined position. After the positioning, the guide pin 82 is pulled out from the blank pipe material 2a before bending.

  In the present embodiment, the same effects as those of the embodiment of FIG. 1 described above can be obtained, and the cored bar member 4 can be easily set at a desired position by the guide pins 82.

  Further, the gap between the guide pin 82 and the guide hole 85 and the gap between the coupling pin 7 and the coupling hole 8 are set to be smaller than the gap between the inner wall surface of the pipe member 2 and the plate member 5 of the core portion 6. Therefore, when the cored bar member 4 is inserted into the pipe member 2, it can be easily inserted.

  In addition, this invention is not limited to the above-mentioned embodiment, Various modifications and application examples can be considered.

  For example, in the above-described embodiment, the disk-shaped flange portion 9 is welded to both ends of the coupling pin 7 to hold and fix the plate material 5 of the core portion 6. Both ends may be crushed to form the flange portion 9, or instead of the flange portion 9, both ends of the coupling pin 7 may be bent to fix the plate member 5 of the core portion 6.

  Moreover, a connection part is not limited to the coupling pin 7, Various things can be considered. For example, the connecting portion may be a wire. In this case, both ends of the wire are welded to the plate material 5 and caulked to hold the plate material 5 of the core portion 6. The connecting portion may be a bolt having a male screw formed on the outer periphery. In this case, the plate member 5 of the core portion 6 is sandwiched and held by a bolt head and a nut screwed into the bolt.

  In addition to the steel material, various materials are conceivable as the material of the plate member 5 of the core portion 6. For example, a resin or a non-metallic material may be used.

  Further, as shown in FIGS. 10 and 11, a hole 10 having a predetermined size may be formed at the center of the plate 5 of the core 6. In this case, the weight of the core part 6 (core metal member 4) can be reduced. Here, as the hole portion 10 is larger, the weight of the cored bar member 4 can be reduced, but the strength is lowered. Therefore, the size of the hole portion 10 is appropriately set in consideration of the weight and strength.

  Further, a spacer may be sandwiched between the plate members 5 of the core portion 6 so as to have a certain interval. For example, when the bending radius of bending is large and the axial length of the bending part 3 is long, the stress (compressive force, tensile force) applied to the bending part 3 is small, and buckling and shrinkage are unlikely to occur. In such a case, the cost of the core part 6 (core metal member 4) can be reduced by sandwiching a spacer between the plate members 5 of the core part 6.

  The cored bar member 4 is not limited to that of the above-described embodiment. For example, the cored bar member 4 is fitted in the bent part 3 and is similar to the bent part 3 in the axial direction along the bent part 3. A pipe material or the like extending in a cross-sectional shape may be used.

  Further, the cross section of the pipe material is not limited to a rectangular cross section, and various ones such as a round cross section are conceivable. For example, as shown in FIGS. 12 and 13, the pipe material 12 may be a modified steel pipe having a modified cross section. In this case, the plate member 13 of the core portion 6 is formed in a modified cross section in the same manner as the modified steel pipe 12. Is preferred.

  Furthermore, as shown in FIG. 12, when the pipe material is a modified steel pipe 12, the gap between the modified steel pipe 12 and the cored bar member 4 (plate material 5) may be adjusted depending on whether or not it is a deformable part. . For example, in the illustrated example, the corner C is a deformable part, and the gap between the deformed steel pipe 12 and the cored bar member 4 at the corner C is set large. More specifically, the roundness (R) is attached to the corner C of the modified steel pipe 12 with a predetermined radius, and the roundness (R) is applied to the corner of the plate 13 with a radius larger than the corner C. Attached.

  Thereby, since the distortion by bending concentrates on the displaceable corner | angular part C, distortion of a non-deformable part, such as the surface part F (side part in a cross section) to which another member is attached, can be reduced. For example, in the cab 61 of FIG. 6, the accuracy of the surface portions of the front pillar portion 62 and the roof rail portion 65 to which the front window 63 and the roof panel 67 are attached can be improved.

FIG. 1 is a schematic sectional view of a structural member according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the structural member of the present embodiment, showing a state before bending. FIG. 3 is an enlarged view of part III in FIG. FIG. 4 is a view taken in the direction of the arrow IV in FIG. FIG. 5 is a schematic structural diagram of the press according to the present embodiment. FIG. 6 is a schematic perspective view of the cab of this embodiment. FIG. 7 is a cross-sectional view of a cored bar member according to another embodiment. FIG. 8 is a cross-sectional view of a cored bar member and a jig according to another embodiment. 9 is a view taken in the direction of the arrow IX in FIG. FIG. 10 is a cross-sectional view of a cored bar member according to a modified example of the present invention. 11 is a view taken in the direction of the arrow XI in FIG. FIG. 12 is a cross-sectional view of a cored bar member according to a modified example of the present invention. 13 is a view taken in the direction of the arrow XIII in FIG. FIG. 14 is a view for explaining pipe bending by conventional press forming.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Structural member 2 Pipe material 3 Bending part 4 Core metal member 5 Board | plate material 6 Core part 7 Connecting pin (connection part)

Claims (5)

In structural members formed by bending pipe material by press molding,
Inserting a cored bar member that supports the inner wall surfaces on the inner side and the outer side of the bent portion in order to prevent buckling and shrinkage of the bent portion, into the bent portion where the pipe material is bent, A structural member characterized in that a pipe material is bent and the cored bar member is deformed integrally with the bent part, and the deformed cored bar member is used as a strength member of the bent part after the bending process.   The core member includes a core portion formed by arranging a plurality of plate materials having the same shape as the cross-sectional shape of the bent portion along the axial direction of the pipe material, and the plate material of the core portion in the axial direction. The structural member according to claim 1, further comprising a connecting portion that is connected and deformed by the bending process.   The structural member according to claim 2, wherein the core member has an axial length of the core portion equal to a length of the bent portion.   The structural member according to any one of claims 1 to 3, wherein a core portion of the cored bar member is welded to an inner wall of the bent portion after the bending process.   The structural member according to any one of claims 1 to 4, comprising a front pillar portion and a roof rail portion formed integrally with a cab of a construction machine.

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