JP7730102B2 - Method for manufacturing rectangular pipe-shaped curved long material and method for forming curved channel material - Google Patents

Description

The present invention relates to a method for producing curved elongated members with a square pipe-shaped cross section, and a method for bending channel members, which are elongated members having a web and a pair of flanges on both sides of the web.

When producing curved elongated materials (hereinafter sometimes referred to as "curved elongated materials"), it is common to curve a straight elongated material using a bender, as described in the following patent document:

JP 2010-162557 A

When forming curves using a bender as described in the above patent documents, a roll mold (inner mold) to be placed on the inside of the curved section must be prepared according to the radius of curvature of the curve. Therefore, if only a small number of molded products (small lots) are to be produced, the cost of producing the roll molds becomes relatively high. Furthermore, for molded products that have curved sections with different radii of curvature, the cost of producing the roll molds becomes significantly high. Therefore, a practical method for producing a small number of curved long materials is desired. The present invention was made in consideration of this situation, and its objective is to provide a highly practical method for producing curved long materials with a square pipe-shaped cross section, and a highly practical method for forming curves in long channel materials.

In order to solve the above problems, the method for manufacturing a rectangular pipe-shaped curved long material of the present invention comprises the steps of:
A method for producing a curved elongated material having a square pipe cross section, comprising:
a channel member preparing step of preparing a pair of straight channel members, each of which is an elongated member having a web and a pair of flanges on both sides of the web;
a channel material bending process in which the pair of channel materials are arranged facing each other with the flanges overlapping each other, and a certain portion in the longitudinal direction is supported by a metal abutment, and while holding a portion on one end side from the aforementioned portion, a portion on the other end side from the aforementioned portion is pushed to bend the pair of channel materials at the portion supported by the metal abutment, and this bending process is repeated while shifting the portion supported by the metal abutment, thereby bending the pair of channel materials together;
and a welding step of welding the flanges of the pair of curved channel members together.
Further, the method for forming a curved channel member of the present invention includes the steps of:
A method for forming a channel material, which is a long material having a web and a pair of flanges on both sides of the web, into a curved shape, comprising:
a bending step in which a certain point in the longitudinal direction of the channel material is supported by a metal backing and a portion on one end side of the point is held, and a portion on the other end side of the point is pressed to bend the channel material at the point supported by the metal backing;
The method is characterized in that a channel material different from the channel material is used, and the channel material and the other channel material are placed opposite each other so that the flanges overlap each other, and then curved , and the channel material is curved by repeatedly performing this while shifting the positions supported by the abutments.
The channel material bending method of the present invention can be considered as a method having a higher concept than the channel material bending step in the above-mentioned method for manufacturing a curved long material in the shape of a square pipe of the present invention, and one of the two channel materials may be used as a dummy channel (cover channel) to play a supporting role in allowing the other channel material to be properly bent.

In the method for manufacturing curved elongated materials in the shape of square pipes of the present invention, specifically the channel material bending process thereof, and the channel material bending method of the present invention, the elongated material, the channel material, is curved by repeatedly bending the material. Specifically, bends with a smaller radius of curvature than the radius of curvature of the original curve are applied while shifting the position of the bend. In other words, the channel material is shaped into an approximate curve by connecting bends with small radii of curvature at a distance. The method for manufacturing curved elongated materials in the shape of square pipes of the present invention makes it possible to easily manufacture even a small number of curved elongated materials without having to prepare relatively expensive roll molds to match the curve. Similarly, the method for bending channel material of the present invention makes it possible to easily curve even a small number of channel materials without having to prepare expensive roll molds to match the curve.

Aspects of the invention

The present invention's method for manufacturing curved, long, square pipe-shaped materials and method for forming curved channel materials can be widely applied to long materials made of general metal materials that undergo plastic deformation, such as steel and aluminum alloys.

The channel material preparation process in the method for manufacturing curved elongated material in the shape of a square pipe of the present invention (hereinafter sometimes simply referred to as the "curved elongated material manufacturing method") may be a process in which channel material of the intended shape and dimensions is purchased, or it may be a process in which plate material is cut to the specified dimensions by shearing or the like, and the cut pieces are then bent using a brake press or the like.

In the channel bending step (hereinafter sometimes simply referred to as the "bending step") of the curved elongated material manufacturing method of the present invention, and in the channel bending method (hereinafter sometimes simply referred to as the "bending method") of the present invention in which a channel other than the channel is bent together with the flanges of the channel facing each other so that they overlap, when two channel members are faced each other, both of the pair of flanges of one of the two channel members may be inside the pair of flanges of the other of the two channel members, or one of the pair of flanges of one of the two channel members may be inside one of the pair of flanges of the other of the two channel members, and the other of the pair of flanges of the other of the two channel members may be inside the other of the pair of flanges of the first of the two channel members. Simply put, one of the two channels may be placed over the other, or the two channels may be combined in an alternating pattern.

In addition, the direction of curvature in the curving process of the curved elongated material manufacturing method of the present invention and the curvature method of the present invention is not particularly limited, but may be, for example, such that the web of the channel material is on the inside of the curve and the tips of the pair of flanges are on the outside of the curve, or such that the web of the channel material is on the outside of the curve and the tips of the pair of flanges are on the inside of the curve. The material may be curved in a so-called "horizontal" direction. On the other hand, the material may be curved such that one of the pair of flanges is on the inside of the curve and the other is on the outside of the curve. The material may be curved in a so-called "vertical" direction.

The bending process of the curved elongated material manufacturing method of the present invention and the bending method of the present invention can be performed, for example, using a jig having two side plates arranged to sandwich the channel material and a stopper provided between the side plates. The channel material is placed in the jig, and the bending process is carried out by pressing a location a predetermined distance longitudinally from the stopper with, for example, a hydraulic piston. By appropriately setting the location supported by the stopper and the amount of pressing (push stroke) by the plunger, etc., it is possible to bend the channel material into a curved shape that approximates a curved shape with a desired radius of curvature.

For example, when a channel material is bent in the vertical direction, the flange on the outer side of the bend will be relatively deeply concave, while the flange on the inner side of the bend will develop wavy wrinkles. To mitigate this phenomenon as much as possible, in the bending process of the curved elongated material manufacturing method of the present invention and in the bending process of the present invention, in which two channel materials are placed face-to-face, a material that functions as a core (also called a "mandrel") may be filled into the space surrounded by the two channel materials at the bent portion. In other words, the core filling process can be performed before the bending process. This filled material can be, for example, hard urethane rubber or a laminate of flexible plate material. Furthermore, the two channel materials placed face-to-face may be covered with another channel material before the bending process of the curved elongated material manufacturing method of the present invention and the bending process of the present invention. The material that served as the core may be removed, for example, by separating the two channel materials after bending them. In other words, the core bar removal process may be carried out after the bending process.

In the curved elongated material manufacturing method of the present invention, after the bending process, the flanges of a pair of curved channel materials are welded together. This welding can be performed, for example, by fillet welding or stopper welding when the flanges are overlapped, or by butt welding when the flange tips are butted together.

1 is a diagram illustrating a side member of an automobile chassis frame, which is a curved long material to which the method for manufacturing a curved long material in the shape of a square pipe of an embodiment is applied. FIG. 1A to 1C are diagrams for explaining a cross section of a side member to be manufactured and a manner in which the side member is divided and manufactured. 1A and 1B are diagrams showing a designed curved elongated member to be produced and an actually produced curved elongated member. FIG. 10 is a schematic perspective view showing how a channel material, which is a long material, is bent at a certain location when the channel material is formed into a curve. FIG. 10 is a diagram showing how the channel material is curved by repeatedly bending the bent portion while shifting the bent portion. FIG. 1 is a diagram showing a curve forming device used when curving a long material. 10 is a diagram showing a state in which two channel members are placed opposite each other during bending, and a state in which a means for preventing deformation of the curved portion of the core metal or the like is provided. FIG.

The following describes in detail, with reference to the drawings, an embodiment of the present invention, a method for manufacturing a curved elongated material in the shape of a square pipe, and the included method for forming a curved channel material. In addition to the embodiment below, the present invention can be implemented in a variety of forms, including those described in the above section "Modes of the Invention," with various modifications and improvements based on the knowledge of those skilled in the art.

[A] Curved elongated member to be manufactured The curved elongated member to be manufactured by the method for manufacturing a curved elongated member in the shape of a square pipe according to the embodiment is the left and right side members 10R, 10L that constitute the chassis frame of an automobile, as shown in FIG. 1(a). The left and right side members 10R, 10L are symmetrical, and the manufacturing methods for each of them differ only due to this symmetry. In light of this, the following description will focus only on the right side member 10R, which is representative of the side members 10R, 10L. In the following description, the side members 10R, 10L may sometimes be collectively referred to as the side member 10.

As shown in the front view of Figure 1(b), the side member 10 has curved portions 12f1, 12f2, 12r1, and 12r2 on the front and rear sides that are curved in the up-down direction, in other words, curved portions that are vertically curved. Furthermore, as shown in the plan view of Figure 1(c), the side member 10 has two curved portions 12c1 and 12c2 in the center in the fore-and-aft direction that are curved in the vehicle width direction, in other words, curved portions that are horizontally curved. Note that curved portions 12f1, 12f2, 12r1, 12r2, 12c1, and 12c2 may be collectively referred to as curved portions 12 when there is no need to distinguish between them.

The side member 10 has a cross section that is generally in the shape of a square pipe. It could also be produced by bending a long piece of square pipe using a pipe bender. However, since this chassis frame is a prototype and only a small number of side members 10 need to be produced, taking into consideration the manufacturing costs of the pipe bender's roll mold and the difficulty of dealing with deformation (dents, wrinkles, etc.) in the curved portion when bending using a core wire or the like, the side member 10 is produced by joining two long channel members 14, as shown in the cross-sectional view of Figure 2(a). One of the two channel members 14 is the outer channel member 14o located on the outside of the vehicle, and the other is the inner channel member 14i located on the inside of the vehicle. When there is no need to distinguish between them, they will be collectively referred to as channel members 14.

The outer channel 14o and the inner channel 14i are made of the same type of steel material, but have different thicknesses, as shown in FIG. 2(a). If the thickness of the outer channel 14o is t _o and the thickness of the inner channel is t _i , the outer channel 14o is thicker than the inner channel 14i. In other words, t _o > t _i . Both the outer channel 14o and the inner channel 14i have a web 14w and a pair of flanges 14f on both sides of the web 14w. The outer channel 14o and the inner channel 14i are joined together with the flanges 14f overlapping each other, specifically, with the inner surfaces of the pair of flanges 14f of the outer channel 14o in contact with the outer surfaces of the pair of flanges 14f of the inner channel 14i. More specifically, the tip of each of the pair of flanges 14f of the outer channel member 14o and the outer surface of each of the pair of flanges 14f of the inner channel member 14i are joined by fillet welds W.

As shown in Figure 2(b), the side member 10 is made by fabricating three pieces and joining the three pieces longitudinally. The three pieces, from the front of the vehicle, can be called the front piece 10f, the center piece 10c, and the rear piece 10r. The front piece 10f includes the curved portions 12f1 and 12f2, the center piece 10c includes the curved portions 12c1 and 12c2, and the rear piece 10r includes the curved portions 12r1 and 12r2.

As can be seen from FIG. 2(b), at the joint between the front piece 10f and the center piece 10c, the outer channel member 14o of the front piece 10f extends longitudinally from the inner channel member 14i, and the inner channel member 14i of the center piece 10c extends longitudinally from the outer channel member 14o. Similarly, at the joint between the rear piece 10r and the center piece 10c, the outer channel member 14o of the rear piece 10f extends longitudinally from the inner channel member 14i, and the inner channel member 14i of the center piece 10c extends longitudinally from the outer channel member 14o. In other words, to improve the joint strength, the outer channel members 14o and the inner channel members 14i are joined alternately. Note that at the joint, the outer channel members 14o and the inner channel members 14i are joined by butt welding.

[B] Method of Manufacturing Curved Long Member As explained above, the side member 10 is manufactured by separately manufacturing the front piece 10f, the center piece 10c, and the rear piece 10r and joining them together. Each of the front piece 10f, the center piece 10c, and the rear piece 10r can be considered a curved long member. Hereinafter, the front piece 10f, the center piece 10c, and the rear piece 10r will be collectively referred to as the curved long member 10T, and a method of manufacturing the curved long member 10T will be explained. In the following explanation, the channel members themselves constituting the curved long member 10T may be referred to as the channel member 14, the outer channel member 14o, and the inner channel member 14i.

The production of the curved elongated member 10T generally includes a channel member preparation process in which a pair of channel members 14, namely, a straight outer channel member 14o and an inner channel member 14i, is prepared; a channel member curving process in which the outer channel member 14o and the inner channel member 14i are curved together; and a welding process in which the flanges 14f of the curved outer channel member 14o and the inner channel member 14i are welded together. Each of these processes is described in detail below.

(a) Channel Preparation Step If at least one of the outer channel 14o and the inner channel 14i has a commercially available shape and size, for example, it is sufficient to purchase that one. However, if either the outer channel 14o or the inner channel 14i is not commercially available, in other words, if it is not a standard size, it is sufficient to prepare the channel 14 itself. Specifically, a plate having a thickness t required for the channel 14 to be prepared is cut to the desired dimensions by shearing or the like, and the cut plate is then bent by a brake press or the like to obtain a straight channel 14 having the desired web width and flange width. The method for preparing this channel 14 is a common method in sheet metal processing, so a detailed description thereof will be omitted.

(b) Channel material curve forming process
i) Basic Method This channel bending process is a process for bending the outer channel 14o and the inner channel 14i together, but it can also be performed for only one channel 14. Therefore, the basic method of the channel bending process will be described by taking bending of one channel 14 as an example. Note that this channel bending process is an example of a channel bending method.

If the curved elongated member 10T to be manufactured in the design is designated as a standard curved elongated member 10T ^* , the standard curved elongated member 10T ^* has one curved portion 12 consisting of three consecutive curved regions A, B, and C, as shown in FIG. 3( a). Each of the curved regions A, B, and C is curved such that one of the pair of flanges 14f of the channel member 14 is on the inside of the curve and the other is on the outside of the curve. The curved regions A and B are curved in the same direction, and the radius of curvature R (the radius of curvature of the outer surface of the inner flange 14f) is R _A for curved region A and R _B (>R _A ) for curved region B. Meanwhile, the curved region C is curved in the opposite direction to the curved regions A and B, and its radius of curvature _R is equal to the radius of curvature R _B of curved region B. Incidentally, the curved region A, curved region B, and curved region C have angle ranges θ _A , θ _B , and θ _C , respectively.

Explaining with reference to Fig. 3(b), the channel member curvature forming process is a process for realizing a curved long member 10T having a shape similar to the standard curved long member 10T ^* by performing a plurality of bending operations at intervals with a basic radius of curvature _R0 , which is a radius of curvature R smaller than the radii of curvature _R0 , _{R0 ,} and R0 of the standard curved long member 10T ^* . The above-mentioned "bending" has a smaller radius of curvature R than "curving," and will be referred to as "bending" hereinafter to distinguish it from curvature. In short, the channel member curvature forming process can be considered as a process for curving the channel member 14 by repeatedly performing a bending process in which the channel member 14 is bent at the basic radius of curvature _R0 .

In Figure 3(b), the bent portions 16, which are the portions that are bent in each bending process, are numbered in the order in which the bending processes are performed, and the straight portions 18, which are the portions that are not bent, are shown shaded between the bent portions 16.

As shown diagrammatically in Figure 4, the bending process involves supporting the area that will become the bent portion 16 from below with abutment 20, holding the portion on one end of the support point with a receiving metal 22, and pressing down the area on the other end with a piston. More specifically, to bend the material vertically, one of the pair of flanges 14f of the channel material 14 is supported by abutment 20, the other is held by receiving metal 22, and the other is pressed down with a piston. Incidentally, only the pressing head 24 attached to the tip of the piston is shown in the figure.

In the bending process as described above, forces as shown in the figure act on the push-down head 24 of the piston, the abutment 20, and the receiving plate 22, so that the channel material 14 is bent at the bending portion 16. Note that the holding by the receiving plate 22 only prevents one end side from jumping up from the portion that will become the bending portion 16 when pushed down by the piston, but it may also be configured to prohibit movement of the channel material 14 in the longitudinal direction. Note that, in consideration of springback of the channel material 14, the abutment 20 has an upper surface that is a partially cylindrical side surface having a radius that is somewhat smaller than the basic radius of curvature _R0 .

By fixing the contact-head distance _L0 , which is the distance between the contact 20 and the contact head 24 of the piston in the longitudinal direction, and appropriately setting the contact-channel-end distance L, which is the distance between one end of the channel 14 and the contact 20 in the longitudinal direction, the pressing amount S of the press head 24, and the pressing force F of the press head 24, it is possible to bend the channel 14 by any amount at any position. Note that it is desirable to set the pressing amount S and the pressing force F while taking into consideration the springback of the channel. Furthermore, instead of the pressing force F, a force acting on the receiving plate 22 or the contact 20 may be used.

Then, by repeating the bending process while feeding the channel material 14 in the feed direction shown in the figure, in other words, while shifting the bent portion 16, which is the portion supported by the abutment 20, toward one end, the channel material 14 can be curved appropriately. The curved elongated material 10T shown in Figure 3(b) can be curved by performing the bending process ten times, as shown in Figure 5. The process numbers in Figure 5 correspond to the numbers of the bent portion 16 in Figure 3(b). As can be seen from the figure, the channel material 14 is turned upside down between the seventh and eighth processes.

Note that while the basic method for bending one channel member 14 has been described here, as previously explained, this channel member bending process is performed on each of the front piece 10f, center piece 10c, and rear piece 10r, and involves bending the outer channel member 14o and inner channel member 14i together.

ii) Channel bending device The channel bending step is performed using a channel bending device (hereinafter, sometimes simply referred to as the "bending device") as shown in a perspective view in Fig. 6(a). This bending device includes a jig 32 having a pair of base plates 30 arranged at an interval from each other, and a hydraulic cylinder 34 attached to the jig 32.

Explaining further with reference to the front view of Figure 6(b), the jig 32 allows the spacing between the pair of substrates 30 to be adjusted by replacing the spacers 36. This spacing is changed between the front piece 10f and rear piece 10r, which are curved vertically, and the center piece 10c, which is curved horizontally. Incidentally, when bending the front piece 10f and rear piece 10r, the overlap between the flanges 14f of the outer channel member 14o and inner channel member 14i is larger than shown in Figure 2(a), so the spacing between the pair of substrates 30 is set based on the width of the flange 14f of the outer channel member 14o. On the other hand, when bending the center piece 10c, the spacing between the pair of substrates 30 is set based on the width of the web 14w of the outer channel member 14o.

Abutment 20 is placed between a pair of substrates 30, and a rod-shaped receiving metal 22 is placed so as to penetrate the pair of substrates 30. The pressing head 24 is detachably attached to the tip of the piston 38 of a hydraulic cylinder 34. Pressurized hydraulic oil is supplied to the hydraulic cylinder 34 from a hydraulic unit (not shown). The abutment 20 and pressing head 24 are positioned and attached in accordance with the spacing between the pair of substrates 30.

Furthermore, the bending device may be equipped with, for example, a laser displacement meter 40 to determine the above-mentioned pressing amount S, a stopper device 44 that moves the stopper 42 by servo control to manage the above-mentioned distance L between the backing channel ends, and a load sensor 46 having a strain gauge, load cell, etc., may be provided on the piston 38 to measure the above-mentioned pressing force F. By utilizing data related to the bending process obtained by the displacement meter 40, stopper device 44, load sensor 46, etc., it is possible to repeatedly perform bending of the channel material 14 with high precision.

iii) Dealing with Deformation of Curved Portions When a long material is curved, deformation occurs at the curved portion. Specifically, for example, a depression occurs at the outer portion of the curve, and a wavy surface, i.e., wrinkles, occurs at the inner portion. When the long material is a channel material, it is not symmetrical in either the left-right or the top-bottom direction, and therefore deformations specific to the channel material, such as changes in the angle between the flange and the web, may occur. Taking this into consideration, the channel material curve-forming process is performed by arranging a pair of channel materials 14, i.e., an outer channel material 14o and an inner channel material 14i, facing each other so that their flanges 14f overlap, as shown in FIG. 7( a). In other words, the two channel materials 14 are curved simultaneously and together not only to improve productivity by simultaneously bending the two channel materials 14, but also to obtain the advantage that one of the pair of channel materials 14 serves as a support for the other and vice versa.

Furthermore, in this channel material bending process, as shown in FIG. 7(b), a dummy channel (cover channel) 50, which functions as a supporter, is placed over the outer channel material 14o, and the space surrounded by the outer channel material 14o and the inner channel material 14i in the curved portion is filled with an object (hereinafter sometimes simply referred to as the "mandrel") 52. The mandrel 52 shown in FIG. 7(b) is made of hard urethane. Alternatively, as shown in FIG. 7(c), the mandrel 52 may be formed by stacking plates 52p according to the direction of bending. The action of the dummy channel 50 and mandrel 52 as described above effectively suppresses the above-mentioned deformation of the curved portion 12 of the curved elongated material 10T.

The core 52 can be filled before the bending process begins. In other words, the core filling process can be performed before the bending process. The core 52 can be removed after the bending process is completed, by separating the curved outer and inner channel members 14o, 14i from each other. In other words, the core removal process can be performed after the bending process. When bending a long rectangular pipe, designing, setting, and adjusting the appropriate core is a relatively difficult and cumbersome task. However, in this channel bending process, the core 52 can be easily filled when the outer and inner channel members 14o, 14i are brought together, and the core 52 can be easily removed by separating the outer and inner channel members 14o, 14i, even though they are curved.

(c) Welding Process In the welding process, the outer channel member 14o and the inner channel member 14i, which have been curved through the channel member bending process, are first set using an appropriate jig so as to be in the state shown in FIG. 2(a). In this set state, the flanges 14f are fillet welded together by a fillet weld W, as shown in the figure. This fillet welding does not need to be performed continuously over the entire length of the curved elongated member 10T as long as an appropriate strength can be obtained. For example, it may be performed by tack welding at an appropriate pitch. Welding may be performed by an appropriate method, such as _CO2 arc welding or TIG welding, depending on the material of the curved elongated member 10T. Since this welding process is a common process, a detailed description thereof will be omitted.

10: Side member (curved long member) 10T: Curved long member 10T ^* : Standard curved long member 12: Curved portion 14: Channel member 14o: Outer channel member 14i: Inner channel member 14w: Web 14f: Flange 16: Bent portion 18: Straight portion 20: Contact metal 22: Receiving metal 24: Press-down head 30: Base plate 32: Jig 34: Hydraulic cylinder 38: Piston 40: Displacement meter 42: Stopper 44: Stopper device 46: Load sensor 50: Cover channel 52: Object functioning as core metal 52p: Plate

Claims (7)

A method for producing a curved elongated material having a square pipe cross section, comprising:
a channel member preparing step of preparing a pair of straight channel members, each of which is an elongated member having a web and a pair of flanges on both sides of the web;
a channel material bending process in which the pair of channel materials are arranged facing each other with the flanges overlapping each other, and a certain portion in the longitudinal direction is supported by a metal abutment, and while holding a portion on one end side from the aforementioned portion, a portion on the other end side from the aforementioned portion is pushed to bend the pair of channel materials at the portion supported by the metal abutment, and this bending process is repeated while shifting the portion supported by the metal abutment, thereby bending the pair of channel materials together;
a welding step of welding the flanges of the pair of curved channel members together. A method for manufacturing a curved elongated material in the shape of a square pipe as described in claim 1, wherein, in the channel material bending process, each of the pair of channel materials is bent so that one of the pair of flanges of each of the channel materials faces inward and the other faces outward. Before the bending step, a core metal filling step is performed in which a space surrounded by the pair of channel materials is filled with an object functioning as a core metal in a portion to be bent, the space being surrounded by the pair of channel materials with the flanges overlapping each other;
3. A method for manufacturing a curved elongated material in the shape of a square pipe according to claim 1 or claim 2, further comprising the step of separating the pair of curved channel members from each other after the bending step is completed, and then performing a core bar removal step to remove the object that has functioned as the core bar. A method for manufacturing a rectangular pipe-shaped curved elongated material according to any one of claims 1 to 3, in which the channel material curving step is carried out by placing a pair of channel materials facing each other and covering them with another channel material. A method for forming a channel material, which is a long material having a web and a pair of flanges on both sides of the web, into a curved shape, comprising:
a bending step in which a certain point in the longitudinal direction of the channel material is supported by a metal backing and a portion on one end side of the point is held, and a portion on the other end side of the point is pressed to bend the channel material at the point supported by the metal backing;
The channel material bending method uses a channel material different from the channel material, and bends the channel material by placing the channel material and the other channel material opposite each other so that the flanges overlap each other, and repeating this while shifting the positions supported by the abutments, thereby bending the channel material. The channel bending method according to claim 5, wherein the bending process is performed by supporting one of the pair of flanges of the channel on the abutment and pressing the other, thereby bending the channel so that one of the pair of flanges of the channel is on the inside of the curve and the other is on the outside. a step of filling a body functioning as a core metal into a space surrounded by the channel material and the other channel material in a portion to be bent, the space being formed by arranging the channel material and the other channel material so that the flanges overlap each other, before the bending step;
7. The method for forming a curved channel member according to claim 5 or 6, further comprising the step of separating the curved channel member and the other channel member from each other after the bending step is completed, and taking out an object that has functioned as the mandrel.