JP7799185B2 - Bending device, method for manufacturing structural member using same, and structural member - Google Patents

Description

This disclosure relates to a folding device, and more specifically to a folding device for folding a material including a web and a flange continuous with the side edge of the web. This disclosure also relates to a method for manufacturing a structural member using the folding device, and to the structural member.

For example, channel steel and angle steel are known structural members used in the exterior wall frames of houses. These structural members generally include a web extending longitudinally of the member and a flange connected to the side edge of the web.

Some structural components are bent into an L-shape. L-shaped structural components are manufactured by preparing two pieces of material, such as channel steel or angle steel, arranging these pieces in an L-shape, and joining their ends together. The ends of the materials are joined by, for example, welding, riveting, or crimping.

Alternatively, L-shaped structural members can be manufactured by bending channel steel or angle steel material. In this case, a notch is formed in the flange of the material, the material is bent at the notch, and then both end faces of the notch are welded together.

However, these manufacturing methods require processes for forming notches in the material and joining the materials together or at the notched areas, which complicates the manufacturing process for structural components and increases their manufacturing costs. Furthermore, when welding is used as the joining method, welding fumes can be generated, which can worsen the working environment. Furthermore, if the material is made of plated steel sheet, welding can remove the plating, potentially compromising the rust resistance of the structural component. As a result, a repair process may be required after welding.

In contrast, Patent Documents 1 and 2 propose methods for manufacturing L-shaped structural members by subjecting a material to plastic processing. The manufacturing methods in Patent Documents 1 and 2 use a mold that includes a pair of front and rear rotary dies, a bending punch positioned above the rotary die, and a pair of left and right pre-bending punches positioned to the sides of the rotary die to perform plastic processing on a material, such as channel steel. In Patent Documents 1 and 2, the pre-bending punches are pressed against both flanges of the material placed on the rotary die, thereby pre-bending each flange. Then, a bending punch with a V-groove at a predetermined angle is pressed from above into the material on the rotary die. At this time, the rotary die rotates along the V-groove of the bending punch, and a portion of each flange is folded inward into the material along the bend line formed by the pre-bending. This forms an L-shaped structural member.

Patent Document 3 proposes a method for manufacturing an L-shaped structural member by drilling holes in each flange of a channel steel material and then bending the material. In the manufacturing method of Patent Document 3, holes are formed in the portion of each flange of the material closest to the web. Then, with the flanges clamped between dies inside and outside the material, a thrust die is used to push the hole portion of the flange from the outside to the inside of the material, folding part of the flange into the inside of the material and bending the material into an L shape.

JP 2009-167787 A JP 2017-170473 A Japanese Patent Application Publication No. 6-262267

For example, when bending a material using the manufacturing methods described in Patent Documents 1 and 2, a bending punch with a V-groove and a pair of front and rear rotary dies must be attached to a press. In Patent Documents 1 and 2, the rotary dies rotate as the bending punch descends, and the material is bent along the V-groove of the bending punch and the rotary dies. During this process, the bent portion of the material is lifted by the rotary dies, causing the material to move as a whole. For example, portions of the material on both sides of the bent portion may change from a horizontal state to a state extending diagonally downward, potentially interfering with the press. Interference with the press is particularly likely when the material to be bent is long. Therefore, a large space must be secured in the press to perform the bending process, resulting in poor space efficiency during the bending process. Furthermore, when bending the material multiple times, it is difficult to avoid interference with the press.

The objective of this disclosure is to provide a folding device that can space-efficiently fold a material that includes a web and a flange that is continuous with the side edge of the web.

The folding device according to the present disclosure is a folding device for folding a material including a web and a flange continuous with the side edge of the web. The folding device comprises an outer mold, an inner mold, and a folding machine. The inner mold is positioned opposite the outer mold. The inner mold is configured to be able to clamp the web together with the outer mold. The folding machine is positioned next to the outer mold. The folding machine is configured to be able to push the web from the outer mold side toward the inner mold side.

The folding device disclosed herein can efficiently fold materials that include a web and a flange that is continuous with the side edge of the web.

FIG. 1 is a perspective view of a bending device according to a first embodiment. FIG. 2 is a plan view of the bending device according to the first embodiment. FIG. 3A is a diagram for explaining a method for manufacturing a structural member using the bending apparatus shown in FIGS. 1 and 2. FIG. FIG. 3B is a diagram for explaining a method for manufacturing a structural member using the bending apparatus shown in FIGS. FIG. 3C is a diagram for explaining a method for manufacturing a structural member using the bending apparatus shown in FIGS. FIG. 3D is a diagram for explaining a method for manufacturing a structural member using the bending apparatus shown in FIGS. FIG. 3E is a diagram for explaining a method for manufacturing a structural member using the bending apparatus shown in FIGS. 1 and 2. FIG. FIG. 3F is a diagram for explaining a method for manufacturing a structural member using the bending apparatus shown in FIGS. FIG. 3G is a diagram for explaining a method for manufacturing a structural member using the bending apparatus shown in FIGS. FIG. 4 is a diagram showing an example of a structural member manufactured using the bending apparatus shown in FIGS. FIG. 5 is a partial plan view of a bending device according to the second embodiment. FIG. 6 is a partially enlarged view of the inner mold of the bending device shown in FIG. FIG. 7 is a diagram for explaining the operation of the bending device shown in FIG. FIG. 8 is a side view showing an example of a structural member manufactured using the bending apparatus shown in FIG. FIG. 9 is a front view showing an example of a structural member manufactured using the bending apparatus shown in FIG. FIG. 10 is a graph showing the depth of sink marks that occurred in the structural members of the examples and the reference example.

The folding device according to this embodiment is a folding device for folding a material including a web and a flange continuous with the side edge of the web. The folding device includes an outer mold, an inner mold, and a folding machine. The inner mold is positioned opposite the outer mold. The inner mold is configured to be able to clamp the web together with the outer mold. The folding machine is positioned next to the outer mold. The folding machine is configured to be able to push the web from the outer mold side toward the inner mold side (first configuration).

When bending a material using the bending device of the first configuration, the web is first clamped between the outer and inner molds. Then, the bending machine pushes the portion of the web that is not clamped between the outer and inner molds from the outer mold side toward the inner mold side, folding part of the flange into the material and bending the material. At this time, the portion of the material located on one side of the bending portion remains fixed by the outer and inner molds, and only the portion of the material located on the other side of the bending portion moves as it is pushed by the bending machine. Therefore, the bending process can be performed in a smaller space than with conventional manufacturing methods. In other words, the bending device of the first configuration makes it possible to fold material in a space-efficient manner.

The bending device of the first configuration can, for example, fold material along a horizontal plane. In this case, the web of material is clamped between the outer and inner molds while standing upright on the floor, and the bending machine is moved horizontally to push the portion of the web that is not clamped between the outer and inner molds toward the inner mold. This makes it possible to fold material even when it is difficult to secure space in the vertical direction.

The bending device of the first configuration allows the material web to be easily folded by using a folding machine to push the material web from the outer mold side toward the inner mold side. This bending device does not need to be installed in large-scale equipment such as a press machine. This eliminates the problem of the folded material interfering with the equipment.

In the bending device according to the first configuration, the bending machine may include a bending die. The bending die is configured to be rotatable around a rotation axis. The rotation axis extends in a direction perpendicular to the surface on which the outer die and inner die are placed (second configuration).

According to the second configuration, the bending die of the folding machine can be rotated around a rotation axis, and this bending die can be used to press the web of material toward the inner die. In this case, the bending angle of the material can be easily changed by changing the rotation angle of the bending die. Therefore, a single folding device can accommodate a variety of bending angles.

The bending device according to the first or second configuration may further include a presser die. The presser die is arranged so as to be stacked on the outer die and inner die (third configuration).

According to the third configuration, the flange of the material can be held down by a presser die when bending the material. In this case, deformation of the flange that would otherwise spread outward from the material when the material is bent by the bending machine can be suppressed.

In the folding device according to any one of the first to third configurations, the inner mold may include an abutment surface and an inclined surface. The abutment surface is a surface for abutting the web and faces the outer mold. The inclined surface is continuous with the end of the abutment surface facing the folding machine. The inclined surface is inclined relative to the abutment surface so as to form an acute angle with the abutment surface (fourth configuration).

With the fourth configuration, the web can be bent along the corner between the contact surface of the inner mold that contacts the web of the material and the inclined surface that is inclined relative to this contact surface. Furthermore, the portion of the flange that is folded inward into the material can be aligned with the inclined surface of the inner mold. This allows for a sharply shaped bent portion to be formed in the material.

In the bending device according to the fourth configuration, the inner mold may further include a padding portion. The padding portion is formed on an inclined surface. The padding portion includes a support surface for supporting the web when the material is folded. The support surface is provided on the bending machine side of the contact surface and non-parallel to the contact surface (fifth configuration).

When bending a material by folding a portion of the flange inward, sink marks may occur at the bent portion of the material. More specifically, as the material is bent, the material may flow in an attempt to reduce the energy required for the bending process, causing the web to dent inward at the bent portion. However, with the fifth configuration, not only is the web clamped between the contact surfaces of the outer and inner molds, but the support surface of the padding on the inner mold can also support the portion of the web that has been bent toward the inner mold by the bending machine. In other words, with the fifth configuration, the material's restraint area by the outer and inner molds can be increased. This reduces the flow of the material during the bending process, preventing sink marks from occurring at the bent portion.

A manufacturing method according to an embodiment is a method for manufacturing a structural member. The manufacturing method includes a preparation step of preparing a raw material including a web and a flange continuous with the side edge of the web; a preforming step of forming a preformed portion on the flange that is recessed inward of the raw material; and a folding step of folding the raw material using a folding device according to any one of the first to fifth configurations after the preforming step. The preformed portion includes a first ridge portion and a second ridge portion. The first ridge portion is the bottom of the preformed portion. The first ridge portion extends from the side edge of the web toward the end of the flange opposite the web. The second ridge portions are both edge portions of the preformed portion. Each of the second ridge portions extends from the web-side end of the first ridge portion toward the end of the flange so as to become more distant from the first ridge portion as it approaches the end of the flange. The folding process includes a step of clamping the web between an outer mold and an inner mold on one side of the first ridge line, and a step of pushing the web from the outer mold side toward the inner mold side using a folding machine on the other side of the first ridge line, thereby folding the preformed portion into the inside of the material along the first ridge line and second ridge line (sixth configuration).

The structural member according to this embodiment comprises a web, a flange, and multiple folded portions. The flange is continuous with the side edge of the web. At each folded portion, a portion of the flange is folded inwardly into the structural member, thereby causing the structural member to be folded (seventh configuration).

The structural member according to this embodiment comprises a web, a flange, and a bent portion. The flange is continuous with the side edge of the web. The bent portion is a portion of the structural member that is bent by folding a portion of the flange inward. The depth of the depression formed in the bent portion is 1.0 mm or less, based on a straight line that touches both ends of the web in the width direction at the bent portion when the structural member is viewed in a direction perpendicular to the web (eighth configuration).

Embodiments of the present disclosure will be described below with reference to the drawings. In each drawing, identical or equivalent components are designated by the same reference numerals, and the same descriptions will not be repeated.

First Embodiment
[Configuration of bending device]
Fig. 1 is a perspective view of a bending device 10 according to a first embodiment. Fig. 2 is a plan view of the bending device 10. The bending device 10 is an apparatus for bending a blank 20 shown by a two-dot chain line in Figs. 1 and 2. In this embodiment, the blank 20 is a channel steel. The blank 20 includes a web 21 and flanges 22 and 23.

Referring to Figures 1 and 2, the bending device 10 includes an outer die 11, an inner die 12, a folding machine 13, and a press die 14. The bending device 10 further includes a support member 15 and a base 16. In Figure 2, the bending device 10 is shown without the press die 14 to avoid cluttering the drawing.

The outer mold 11 is configured so that it can clamp the web 21 of the material 20 together with the inner mold 12. The outer mold 11 is supported from its back side by a support member 15. The back side of the outer mold 11 is the surface opposite to the inner mold 12 and the web 21 of the material 20. The outer mold 11 is formed integrally with the support member 15, for example. In this embodiment, the outer mold 11 and support member 15 have an elongated shape.

The outer mold 11 is placed on the base 16. The outer mold 11 is detachable from the base 16. When bending the material 20, the outer mold 11 is attached to the base 16 with fastening members 17, such as bolts. The outer mold 11 may be attached to the base 16 via a support member 15. More specifically, the support member 15 may be fastened to the base 16 with one or more fastening members 17, thereby fixing the outer mold 11 supported by the support member 15 to the base 16.

The outer mold 11 includes an abutment surface 111. The abutment surface 111 is provided on the outer mold 11 opposite the support member 15. The abutment surface 111 is a surface that abuts against the web 21 of the material 20. Although not particularly limited, the abutment surface 111 has, for example, a substantially rectangular shape.

The inner mold 12 is positioned opposite the outer mold 11. The inner mold 12 includes an abutment surface 121 and an inclined surface 122. The abutment surface 121 faces the abutment surface 111 of the outer mold 11. The abutment surface 121 is a surface for abutting against the web 21 of the material 20 from the opposite side of the outer mold 11. The inclined surface 122 is continuous with the end of the abutment surface 121 on the folding machine 13 side. The inclined surface 122 is inclined relative to the abutment surface 121 so as to form an acute angle with the abutment surface 121. The abutment surface 121 and the inclined surface 122 may each have a substantially rectangular shape. However, the shapes of the abutment surface 121 and the inclined surface 122 are not limited to this.

The inner mold 12 is placed on the base 16. The inner mold 12 is detachable from the base 16. When bending the material 20, the inner mold 12 is attached to the base 16 by, for example, fastening members 17. The inner mold 12 is fastened to the base 16 by one or more fastening members 17.

The folding machine 13 is arranged next to the outer mold 11. The folding machine 13 is configured to be able to push the web 21 of the material 20 from the outer mold 11 side toward the inner mold 12 side. The folding machine 13 includes a bending mold 131 and a drive device 132.

The bending die 131 is placed on the base 16. The bending die 131 is configured to be rotatable around a rotation axis 133. The rotation axis 133 extends in a direction substantially perpendicular to the surface on which the outer die 11 and inner die 12 are placed. In this embodiment, the rotation axis 133 extends in a direction substantially perpendicular to the surface of the base 16. The bending die 131 is detachable from the base 16.

The bending die 131 has an elongated shape. When the bending process of the material 20 begins, the bending die 131 is arranged in series with the outer die 11. The bending die 131 can press the web 21 of the material 20 by rotating around the rotation axis 133 from a state in series with the outer die 11. The surface of the bending die 131 facing the material 20 is provided with an abutment surface 131a for abutting against the web 21. When the bending die 131 is in series with the outer die 11, the abutment surface 131a can be located on substantially or approximately the same plane as the abutment surface 111 of the outer die 11.

The drive device 132 is configured to operate the bending die 131. The drive device 132 is configured to be able to push the bending die 131 toward the material 20. The drive device 132 is typically an actuator that performs linear motion. The drive device 132 may be, for example, a fluid pressure cylinder such as a hydraulic cylinder or an air cylinder, or may be an electric cylinder. The drive device 132 penetrates the support member 15 and comes into contact with the bending die 131.

When bending the material 20, the pressing die 14 is arranged so as to be stacked on the outer die 11 and inner die 12. The pressing die 14 is detachable from the base 16. The pressing die 14 is attached to the base 16, for example, by fastening members 17. In this embodiment, the pressing die 14 is attached to the base 16 via the outer die 11. For example, the pressing die 14 can be fixed to the base 16 by fastening the pressing die 14 and outer die 11 to the base 16 with one or more fastening members 17.

[Method of manufacturing structural members]
3A to 3G, a method for manufacturing a structural member using the bending apparatus 10 will be described below. The method for manufacturing a structural member includes a preparation step, a preforming step, and a bending step.

(preparation process)
3A , in the preparation step, a raw material 20, for example, a channel steel, is prepared. The raw material 20 includes a web 21 and flanges 22 and 23. The web 21 is flat and extends in the longitudinal direction of the elongated raw material 20. The flange 22 is continuous with one side edge of the web 21. The flange 23 is continuous with the other side edge of the web 21. The flanges 22 and 23 are each flat and face each other in the width direction of the raw material 20. Like the web 21, the flanges 22 and 23 each extend in the longitudinal direction of the raw material 20.

(Preforming process)
In the preforming step, preforming is performed on the prepared material 20. First, referring to Fig. 3B, the mold 30 used in the preforming step will be described. The mold 30 includes a die 31 and punches 32 and 33.

The die 31 has, for example, a generally rectangular parallelepiped shape. The die 31 includes a top surface 311 and side surfaces 312 and 313. The top surface 311 is, for example, rectangular in plan view of the die 31 and extends in the longitudinal direction of the die 31. The side surface 312 is continuous with one side edge of the top surface 311. The side surface 313 is continuous with the other side edge of the top surface 311. Like the top surface 311, the side surfaces 312 and 313 each extend in the longitudinal direction of the die 31.

A recess 314 is provided on each of the side surfaces 312 and 313. The recess 314 has a substantially triangular shape when viewed from the side of the die 31. The recess 314 includes ridge portions 314a, 314b, and 314c. The ridge portion 314a is the bottom of the recess 314 and is in the form of a valley fold. The ridge portion 314a extends substantially or roughly in the height direction of the die 31. When viewed from the side of the die 31, the ridge portion 314a may be perpendicular to the side edge of the top surface 311, or may be inclined relative to the side edge of the top surface 311.

Ridge portions 314b and 314c are both edges of recess 314 and are each fold-like. Ridge portions 314b and 314c extend generally in the height direction of die 31. However, ridge portions 314b and 314c are inclined with respect to ridge portion 314a, which is the bottom of recess 314. The angle between ridge portion 314b and ridge portion 314a is equal to the angle between ridge portion 314c and ridge portion 314a. The angle between each of ridge portions 314b and 314c and ridge portion 314a is, for example, 45°. However, the angle between each of ridge portions 314b and 314c and ridge portion 314a may be less than 45° or greater than 45°.

Punches 32 and 33 are arranged on both sides of the die 31. Punch 32 is arranged to face one side surface 312 of the die 31. Punch 33 is arranged to face the other side surface 313 of the die 31.

Each of the punches 32 and 33 has a protrusion 34 on the surface facing the die 31. The protrusion 34 has a shape corresponding to the recess 314 formed on the side surfaces 312 and 313 of the die 31. When viewed from the die 31 side, the protrusion 34 has a substantially triangular shape. The protrusion 34 includes ridges 34a, 34b, and 34c. The ridge 34a is the top of the protrusion 34, and the ridges 34b and 34c are the base of the protrusion 34. The ridge 34a extends substantially parallel to the ridge 314a of the recess 314 of the die 31. The ridges 34b and 34c extend substantially parallel to the ridges 314b and 314c of the recess 314 of the die 31, respectively.

Referring to Figure 3C, when preforming the blank 20, the blank 20 is first placed on the die 31 with the punches 32 and 33 spaced apart from the die 31. At this time, the web 21 of the blank 20 is positioned on the top surface 311 of the die 31, and the flanges 22 and 23 of the blank 20 are positioned along the side surfaces 312 and 313 of the die 31, respectively. In this state, the punches 32 and 33 are brought close to the die 31 and pressed against the flanges 22 and 23 of the blank 20. As a result, portions of the flanges 22 and 23 are pressed between the recessed portion 314 of the die 31 and the protruding portions 34 of the punches 32 and 33. As a result, a preformed portion 24 is formed on each of the flanges 22 and 23, as shown in Figure 3D.

The preforming portion 24 is a portion of the flanges 22, 23 that is recessed toward the inside of the blank 20. The preforming portion 24 has a substantially triangular shape in a side view of the blank 20, corresponding to the recess 314 (Figure 3B) of the die 31. The preforming portion 24 includes ridge portions 24a, 24b, and 24c. The ridge portion 24a is the bottom of the recessed preforming portion 24 and is in the form of a valley fold. The ridge portion 24a extends from the side edge of the web 21 toward the end of the flange 22 or 23 (the side opposite the web 21). The ridge portion 24a may be perpendicular to the side edge of the web 21 or may be inclined relative to the side edge of the web 21 in a side view of the blank 20.

Ridge portions 24b and 24c are both edge portions of preformed portion 24 and are each fold-like. Ridge portions 24b and 24c extend from the end of ridge portion 24a on the web 21 side toward the end of flange 22 or 23 (the side opposite web 21). However, ridge portions 24b and 24c are inclined relative to ridge portion 24a, which is the bottom of preformed portion 24. Ridge portions 24b and 24c become more spaced apart from ridge portion 24a as they approach the end of flange 22 or 23. Ridge portions 24b and 24c extend, for example, from the connection point of ridge portion 24a to the side edge of web 21 to the end of flange 22 or 23.

The angle between ridge portion 24b and ridge portion 24a is equal to the angle between ridge portion 24c and ridge portion 24a. The angle between each of ridge portions 24b and 24c and ridge portion 24a is, for example, 45°. However, the angle between each of ridge portions 24b and 24c and ridge portion 24a may be less than 45° or greater than 45°. The sum of the angle between ridge portion 24b and ridge portion 24a and the angle between ridge portion 24c and ridge portion 24a, i.e., the angle between ridge portion 24b and ridge portion 24c, is the bending angle of material 20.

The preforming process is a process of forming preformed portions 24, including ridge portions 24a, 24b, and 24c as folding lines, on the flanges 22 and 23 to make it easier to fold the blank 20 in the subsequent folding process. If the blank 20 is to be folded at multiple locations in the folding process, the preforming process can be repeated multiple times to form multiple preformed portions 24 on each of the flanges 22 and 23. For example, if it is desired to fold the blank 20 at multiple locations in the folding process to deform it into a frame shape, four preformed portions 24 can be formed on each of the flanges 22 and 23. The preformed portions 24 on the flange 22 are formed at positions corresponding to the preformed portions 24 on the flange 23.

(Bending process)
3E and 3F , in the folding process, the material 20 after the preforming process is folded by the folding device 10. In this embodiment, an example will be described in which the base 16 is placed on the floor surface and the material 20 is folded along a substantially horizontal plane.

As shown in Figure 3E, in the folding process, the raw material 20 is first placed in the folding device 10. More specifically, the web 21 of the raw material 20 is clamped between the outer mold 11 and inner mold 12 on one side of the ridge portion 24a, which is the valley fold line of the preformed portion 24. The outer mold 11 and inner mold 12 are fixed to the base 16 by the fastening member 17 with the web 21 firmly clamped between them.

When the raw material 20 is placed in the bending device 10, the web 21 stands upright relative to the base 16. One flange 22 is in contact with the surface of the base 16. The other flange 23 is positioned above the flange 22. The outer mold 11 abuts the web 21 from the outside of the raw material 20 using the abutment surface 111 on the inner mold 12 side. The inner mold 12 fits between the flanges 22, 23 and abuts the web 21 from the inside of the raw material 20 using the abutment surface 121 on the outer mold 11 side. The corner of the inner mold 12 between the abutment surface 121 and the inclined surface 122 is positioned at the intersection of the ridge portions 24a and 24b of the preforming portion 24. The inclined surface 122 is positioned so as to follow the ridge portion 24b of the preforming portion 24 in a plan view of the bending device 10.

When the raw material 20 is placed in the bending device 10, the contact surface 131a of the bending die 131 of the folding machine 13 can also come into contact with the web 21. The bending die 131 contacts the web 21, for example, from the outside of the raw material 20. In the bending device 10, the raw material 20 is placed so that the rotation axis 133 of the bending die 131 is located on the opposite side of the outer die 11 and inner die 12, across the ridge portion 24a, which is the valley fold line of the preformed portion 24. The pressing die 14 is placed after the web 21 is clamped between the outer die 11 and inner die 12. The pressing die 14 is placed so as to be stacked on top of the outer die 11 and inner die 12, and presses down on the flange 23 from the outside (above) of the raw material 20. The pressing die 14 is fixed to the outer die 11 and base 16 by fastening members 17.

Referring to Figure 3F, once the material 20 is placed in the folding device 10, the material 20 is folded by the folding machine 13. More specifically, the folding machine 13 presses the web 21 toward the inner mold 12 on the side opposite the outer mold 11 and inner mold 12 from the ridge line 24a (Figure 3E), which is the valley fold line of the preformed portion 24, thereby folding the material 20 while folding the preformed portion 24 into the inside of the material 20 along the ridge lines 24a, 24b, and 24c (Figures 3E and 3F). Note that to avoid cluttering the drawings, the presser die 14 is omitted from Figure 3F and Figure 3G, which will be described later.

The drive unit 132 of the folding machine 13 extends, for example, toward the bending die 131. As a result, the bending die 131 is pushed by the drive unit 132 to rotate around the rotation axis 133. As the bending die 131 rotates, the material 20 is pushed by the bending die 131 and begins to bend. The web 21 bends along the corner between the abutment surface 121 and the inclined surface 122 of the inner die 12 (Fig. 3E). The pre-formed portions 24 of each of the flanges 22 and 23 are folded inward of the material 20 along the ridges 24a, 24b, and 24c (Figs. 3E and 3F). The portions of the flanges 22 and 23 folded inward of the material 20 come into contact with the inclined surface 122 of the inner die 12 (Fig. 3E).

After bending the blank 20 to the specified bending angle, the drive device 132 and bending die 131 are stopped and returned to their initial positions. If no preformed portion 24 remains on the blank 20, the blank 20 is removed from the bending device 10. If a preformed portion 24 remains on the blank 20, the blank 20 is shifted so that the preformed portion 24 is positioned near the bending die 131, as shown in Figure 3G, and the bending process is repeated.

When multiple preformed portions 24 are provided on the flanges 22, 23, it is preferable that the length of the inner mold 12 in the longitudinal direction of the material 20 be shorter than the distance between adjacent preformed portions 24 in the longitudinal direction of the material 20. This is because if the length of the inner mold 12 is equal to or greater than the distance between the preformed portions 24, it will be difficult to remove the inner mold 12 from within the material 20 after repeated bending. The length of the outer mold 11 in the longitudinal direction of the material 20 may be longer than the length of the inner mold 12 in the longitudinal direction of the material 20, or may be equal to the length of the inner mold 12.

[Structural members]
4 is a diagram showing an example of a structural member 40 manufactured using the bending apparatus 10. The structural member 40 includes a web 41, flanges 42 and 43, and a plurality of folded portions 44.

The structural member 40 shown in Figure 4 has four bent portions 44. In other words, the structural member 40 is bent at four locations. This structural member 40 has an overall rectangular frame shape.

At each of the folded sections 44, portions 421, 431 of the flanges 42, 43 are folded inside the structural member 40. More specifically, portions 421, 431 of the flanges 42, 43, which were preformed portions 24 (Figure 3D) formed on the flanges 22, 23 of the blank 20, are folded and positioned inside the structural member 40. The flanges 42, 43 are continuous with both side edges of the web 41. Therefore, at each of the folded sections 44, the web 41 is bent as the flanges 42, 43 are folded in.

One end 45 of the structural member 40 may or may not be joined to the other end 46. The ends 45, 46 of the structural member 40 may be mechanically joined, for example, by crimping.

[effect]
When bending the raw material 20 using the bending device 10 according to this embodiment, the web 21 is first clamped between the outer mold 11 and the inner mold 12. Then, the bending machine 13 pushes the portion of the web 21 that is not clamped between the outer mold 11 and the inner mold 12 from the outer mold 11 side toward the inner mold 12 side, thereby folding a portion of the flanges 22, 23 into the raw material 20 and bending the raw material 20. At this time, the portion of the raw material 20 that is located on the outer mold 11 and the inner mold 12 side, sandwiching the ridge portion 24a of the preformed portion 24, is restrained by the outer mold 11 and the inner mold 12 and remains stationary. During the bending process of the raw material 20, only the portion of the raw material 20 that is located on the bending machine 13 side, sandwiching the ridge portion 24a of the preformed portion 24, is pushed and moved by the bending machine 13. Therefore, the raw material 20 can be efficiently bent in a small space. Therefore, even a relatively long raw material 20 can be bent without worrying about interference with the surrounding area. It is also possible to perform multiple bending processes on the blank 20 .

The bending device 10 according to this embodiment can bend the material 20 along a horizontal plane. For example, the base 16 can be placed on the floor and the bending machine 13 can be moved horizontally. Therefore, the material 20 can be bent even when it is difficult to secure space in the vertical direction.

In the bending device 10 according to this embodiment, the material 20 can be easily bent by moving the bending die 131 toward the inner die 12 using a drive device 132, such as a fluid pressure cylinder. This bending device 10 does not need to be installed in a large-scale facility such as a press machine. This eliminates the problem of the bent material 20 interfering with the facility.

In the bending device 10 according to this embodiment, the bending machine 13 includes a bending die 131. This bending die 131 rotates around a rotation axis 133, thereby pressing the web 21 of the material 20 toward the inner die 12. The rotation angle of the bending die 131 can be easily adjusted, for example, by changing the stroke of the drive unit 132. By adjusting the rotation angle of the bending die 131, structural members 40 with various bending angles can be manufactured using a single bending device 10.

The bending device 10 according to this embodiment is equipped with a press die 14. This press die 14 is capable of pressing down the flange 23 when bending the blank 20. The flange 22 is also pressed down by the base 16. Therefore, when the preformed portions 24 of the flanges 22, 23 are folded in and the blank 20 is bent, deformation of the other portions of the flanges 22, 23 that would otherwise open outward can be suppressed. In other words, the bending process can be performed while maintaining the cross-sectional shape of the blank 20.

In the bending device 10 according to this embodiment, the inner mold 12 includes a contact surface 121 that contacts the web 21 of the material 20, and an inclined surface 122 that is continuous with the contact surface 121. In this case, the web 21 can be bent along the corner between the contact surface 121 and the inclined surface 122. Furthermore, the portions of the flanges 22, 23 that are folded inward of the material 20 can be aligned with the inclined surface 122. This allows for the formation of sharply shaped bent portions in the material 20.

When using the bending device 10 according to this embodiment, a structural member 40 having multiple bent portions 44 can be manufactured. Each bent portion 44 is formed by folding the preformed portion 24 of the flanges 23, 22 of the blank 20 through plastic processing. In this case, each bent portion 44 hardens through work hardening, thereby increasing the strength of the structural member 40 as a whole.

Second Embodiment
5 is a partial plan view of a folding apparatus 10A according to the second embodiment. The folding apparatus 10A has almost the same configuration as the folding apparatus 10 according to the first embodiment. However, the folding apparatus 10A includes an inner die 12A different from that of the folding apparatus 10 according to the first embodiment.

Referring to Figure 5, the inner mold 12A includes a padding portion 123 in addition to the contact surface 121 and the inclined surface 122. The padding portion 123 is formed on the inclined surface 122. More specifically, the padding portion 123 is provided at the end of the inclined surface 122 on the bending machine 13 side. The padding portion 123 includes an extension surface 123a and a support surface 123b.

The extension surface 123a is a surface that extends the contact surface 121 of the inner mold 12A toward the bending machine 13. The extension surface 123a extends from the tip of the contact surface 121 toward the bending machine 13. The extension surface 123a is continuous with the contact surface 121 so that it is flush with the contact surface 121. However, there may be a slight step at the boundary between the extension surface 123a and the contact surface 121, or the extension surface 123a may be slightly inclined relative to the contact surface 121.

The support surface 123b is a surface for supporting the web when the material is folded by the folding device 10. The support surface 123b is positioned closer to the folding machine 13 than the abutment surface 121. The support surface 123b is connected to the abutment surface 121 via the extension surface 123a. The support surface 123b is arranged non-parallel to the abutment surface 121. The angle between the abutment surface 121 and the support surface 123b may be 90°, or may be greater than or less than 90°. The angle between the abutment surface 121 and the support surface 123b can be determined depending on the folding angle of the material.

Figure 6 is a partially enlarged view of the inner mold 12A, showing the inner mold 12A as viewed from the inclined surface 122 side. Referring to Figure 6, the padding 123 has a shape that narrows from the end of the inclined surface 122 toward the inside. The portion of the padding 123 that continues to the support surface 123b (Figure 5) is formed, for example, in a substantially triangular cone (pyramid) shape. The padding 123 is provided on the inclined surface 122 so that it is substantially bilaterally symmetrical when the inner mold 12A is viewed from the inclined surface 122 side.

In this embodiment, both corners 124 of the inner mold 12A on the side of the padded portion 123 are chamfered. In other words, each corner 124 of the inner mold 12A is formed so that it is essentially arc-shaped when viewed from the inclined surface 122 side.

Figure 7 is a diagram illustrating the operation of the bending device 10A. Figure 7 shows the bending device 10A in a plan view when bending the material 20. Referring to Figure 7, when the material 20 is bent, the portion 211 of the web 21 facing the abutment surface 121 of the inner mold 12A is clamped between the outer mold 11 and the inner mold 12A. Meanwhile, the portion 212 of the web 21 not clamped between the outer mold 11 and the inner mold 12A is bent by the bending mold 131 rotating around the rotation axis 133. At this time, the portion 212 of the web 21 pressed and bent by the bending mold 131 is supported by the support surface 123b of the padding portion 123 provided on the inner mold 12A. The support surface 123b of the padding portion 123 supports and restrains the web 21 from inside the material 20. This suppresses the flow of material during the folding process, preventing the formation of depressions (sink marks) in the web 21 on the folded side of the material 20.

When viewed from the side of the inclined surface 122, the padding 123 of the inner mold 12A has a shape that narrows toward the inside of the inclined surface 122. This prevents interference between the preformed portions 24 (Figures 3E and 3F) of the flanges 22, 23 and the padding 123 when they are folded into the inside of the material 20 as the material 20 is bent. Furthermore, because both corners 124 of the inner mold 12A are rounded by R-chamfering, interference between the folded preformed portions 24 and the inner mold 12A can also be prevented.

Figures 8 and 9 are diagrams showing an example of a structural member 50 manufactured using the bending apparatus 10A. Figure 8 is a side view of the structural member 50. Figure 9 is a front view of the structural member 50.

Referring to Figure 8, the structural member 50 comprises a web 51, a flange 52, and a folded portion 53. As with the structural member 40 according to the first embodiment (Figure 4), the flange 52 is provided contiguous with each of the two side edges of the web 51. The folded portion 53 is a portion of the structural member 50 that is folded by folding a portion of the flange 52 inward.

Figure 9 is a view of the structural member 50 viewed in a direction perpendicular to the web 51, showing the portion of the web 51 that corresponds to the portion 212 (Figure 7) on the folded side of the web 21 of the material 20. In Figure 9, the structural member 50 manufactured using the bending device 10A of this embodiment is shown by a solid line, and the structural member on which the sink mark has occurred is shown by a two-dot chain line.

As shown by the two-dot chain line in Figure 9, when a structural member is manufactured by bending a material such as channel steel, sink marks typically occur at the bent portion of the structural member. That is, a significant depression occurs at the bent portion of the structural member relative to the reference line S. In contrast, sink marks do not substantially occur at the bent portion 53 of the structural member 50 according to this embodiment. That is, the depth (maximum depth) of the depression relative to the reference line S at the bent portion 53 of the structural member 50 is 1.0 mm or less. The reference line S is an imaginary straight line that touches both ends of the web 51 in the width direction at the bent portion 53 when the structural member 50 is viewed in a direction perpendicular to the web 51.

The above describes an embodiment of the present disclosure, but the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present disclosure.

In the bending devices 10, 10A according to the above embodiments, the bending machine 13 includes a bending die 131 and a drive device 132. However, the bending machine 13 does not have to include, for example, the bending die 131. The bending machine 13 can also directly push the web 21 of the material 20 using the drive device 132, which is an actuator that performs linear motion. The bending machine 13 only needs to be configured to be able to push the web 21 from the outer die 11 side toward the inner die 12, 12A side.

The bending devices 10, 10A according to the above embodiments are equipped with a press die 14. However, the bending devices 10, 10A do not necessarily have to be equipped with a press die 14. It is also possible to perform the bending process without pressing the flange 23 of the material 20 with the press die 14.

In the above embodiment, in the preforming process of the blank 20, the preformed portions 24 are formed simultaneously on both flanges 22, 23. However, it is also possible to form the preformed portions 24 on one of the flanges 22, 23 and then form the preformed portions 24 on the other flange 22, 23.

In the above embodiment, the blank 20 is a channel steel. However, the material and shape of the blank 20 are not limited to this. The material of the blank 20 may be any metal that can be plastically processed. In addition to steel, materials that can be used for the blank 20 include, for example, aluminum, copper, titanium, and alloys thereof. The blank 20 may have a plating layer. The blank 20 may be angled. That is, the blank 20 may not include one of the flanges 22, 23. Alternatively, the blank 20 may be channel-shaped, with lips attached to the flanges 22, 23. Similarly, the structural members 40, 50 manufactured from the blank 20 may also be angle-shaped or channel-shaped with a lip.

The structural member 40 illustrated in the first embodiment above has four bent portions 44 and has a rectangular frame shape overall. However, the number of bent portions 44 in the structural member 40 may be three or less, or five or more. By adjusting the bending angle of each bent portion 44, the structural member 40 can also have a shape other than a rectangle.

The structural member 50 illustrated in the second embodiment above has a single bent portion 53. However, the structural member 50 may be provided with multiple bent portions 53. The structural member 50 may also have a polygonal shape, for example, similar to the structural member 40 according to the first embodiment.

To confirm the effects of the bending device 10A according to the second embodiment, the bending device 10A was used to bend a material 20 to form a structural member 50 (Example). Furthermore, the bending device 10 according to the first embodiment was used to bend a material 20 to form a structural member 50 similar to the Example (Reference Example). Then, for each of the Example and Reference Example, the depth of sink marks that occurred in the bent portion 53 of the structural member 50 was measured. The sink depth is the depth of the depression that occurred in the bent portion 53 due to the bending process, and is the maximum depth of the depression relative to the reference line S described in the second embodiment.

Figure 10 shows the depth of sink marks that occurred in the structural members 50 of the Example and the Reference Example. Referring to Figure 10, in the structural member 50 of the Reference Example, the depth of the sink marks that occurred in the bent portion 53 was approximately 3.0 mm. On the other hand, in the structural member 50 of the Example, the depth of the sink marks that occurred in the bent portion 53 was 1.0 mm or less. Therefore, it was confirmed that the occurrence of sink marks in the structural member 50 was suppressed by using a bending device 10A equipped with an inner mold 12A provided with a padding portion 123.

10, 10A: Bending device 11: Outer mold 12, 12A: Inner mold 121: Contact surface 122: Inclined surface 123: Padded portion 123b: Support surface 13: Bending machine 131: Bending mold 133: Rotating shaft 14: Pressing mold 20: Material 21: Web 22, 23: Flange 24: Pre-formed portion 24a, 24b, 24c: Ridge portion 40, 50: Structural member 41, 51: Web 42, 43, 52: Flange 44, 53: Bending portion

Claims (7)

1. A folding device for folding a material including a web and a flange continuous with a side edge of the web, comprising:
The outer shape and
an inner mold disposed opposite the outer mold and configured to be able to clamp the web together with the outer mold;
a folding machine disposed adjacent to the outer mold and configured to be able to push the web from the outer mold side toward the inner mold side;
Equipped with
The inner mold is
a contact surface that faces the outer mold and contacts the web;
a flat inclined surface that is continuous with the end of the contact surface on the bending machine side and is inclined relative to the contact surface so as to form an acute angle with the contact surface;
A folding device comprising : The folding device according to claim 1,
The folding machine is
a bending mold configured to be rotatable around a rotation axis extending in a direction perpendicular to a surface on which the outer mold and the inner mold are placed;
A folding device comprising: The folding device according to claim 1, further comprising:
a pressing die arranged to be stacked on the outer die and the inner die;
A bending device comprising: The folding device according to claim 1 ,
The inner mold further comprises:
a padding portion formed on the inclined surface;
Including,
The padding portion is
a support surface provided on the folding machine side of the contact surface and non-parallel to the contact surface, for supporting the web when the material is folded;
A folding device comprising: A method for manufacturing a structural member, comprising:
a preparation step of preparing a blank including a web and a flange continuous with a side edge of the web;
a preforming step of forming a preformed portion on the flange that is recessed inward from the material;
a folding step of folding the material by the folding device according to any one of claims 1 to 4 after the preforming step;
Equipped with
The preforming section is
a first ridge portion at the bottom of the preformed portion, the first ridge portion extending from the side edge of the web toward an end of the flange opposite the web;
a second ridge portion at each of both edge portions of the preformed portion, the second ridge portion extending from the web-side end of the first ridge portion toward the end of the flange so as to become more spaced from the first ridge portion as the second ridge portion approaches the end of the flange;
Including,
The bending step includes:
a step of sandwiching the web between the outer mold and the inner mold on one side of the first ridge line portion;
a step of folding the material while folding the preformed portion into the inside of the material along the first ridge line portion and the second ridge line portion by pushing the web from the outer mold side toward the inner mold side by the folding machine on the other side of the first ridge line portion;
A manufacturing method comprising: A structural member,
The web and
a flange continuous with the side edge of the web;
A plurality of folds;
Equipped with
A structural member, wherein at each of the bent portions, a portion of the flange is folded inward of the structural member, thereby causing the structural member to be in a bent state. A structural member,
The web and
a flange continuous with the side edge of the web;
a bent portion in the structural member, which is a portion where a part of the flange is bent by folding inward;
Equipped with
A structural member in which the depth of the depression occurring in the bent portion is 1.0 mm or less, based on a straight line tangent to both ends of the web in the width direction at the bent portion, when the structural member is viewed along a direction perpendicular to the web.