JP2006305627A - Method for forming curve-shaped channel member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forming method by which twist is hardly generated when forming a curve-shaped hat-channel member and a curve-shaped U-channel member. <P>SOLUTION: The method comprises forming the curved-shaped channel member 1 the vertical wall parts 12, 12 of which are formed through bending parts 14 on both sides of a lateral wall part 11 and the center line of the cross section of which is curved. When calling a region to approximately a quarter of the length of the member along the center line of the cross section forward the side of the center in the direction of a curved periphery from the end parts of the curve-shaped channel member 1 as a quarter region, twist suppressing parts R where tensile stress are immanent in the inside and compressing stress in the outside along the height direction is formed in the upper part of vertical wall parts 12, 12 which are present at least in the quarter region of both end sides of the curve-shaped channel member 1 which is held in the forming die when the forming is finished. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of forming a curved channel member used as a vehicle body structural member of various transportation equipment such as an automobile, and more particularly to a method of suppressing twisting of a member that occurs after being released from a mold.

  In recent years, with the aim of improving fuel efficiency, consideration for the environment, safety, etc., the strengthening and weight reduction of automobile bodies and parts have been promoted. As one of the means, body structural members (frame members, For member members) and panels (outer plate, inner plate), etc., the steel plates are being strengthened (high tensile) and are being converted to lightweight materials such as aluminum alloy plates.

As a typical cross-sectional shape of the structural member, as shown in FIG. 1 (1), a lateral wall portion (web) 11 and bent portions 14 and 14 (curvature radius rp) are provided at both ends of the lateral wall portion 11. A hat shape comprising bent vertical wall portions 12, 12 and flange portions 13, 13 bent outwardly through bent portions 15, 15 (curvature radius rd) at the end of each vertical wall portion 12. As shown in FIG. 1 (2), there are channel members and U-shaped channel members that do not have flange portions 13 and 13 with respect to the hat-shaped channel member. In the illustrated example, the vertical wall portion 12 is bent perpendicularly to the horizontal wall portion 11, but may be formed in an inclined shape. In the present invention, the hat-shaped channel member and the U-shaped channel member are collectively referred to as a channel member.
The cross-sectional shape of the hat-shaped channel member has a width (inner width between the vertical wall portions 12 and 12) W, a height (height from the lower surface of the flange portion 13 to the upper surface of the horizontal wall portion 11) H, and a flange portion. 13, width Lf (length from the tip of the flange portion 13 to the inner surface of the vertical wall portion 12), the radius of curvature rp of the bent portion 14 that transitions from the horizontal wall portion 11 to the vertical wall portion 12, and the vertical wall portion 12 to the flange portion It is specified by the radius of curvature rd of the bent portion 15 that shifts to 13. The U-shaped channel member is similarly identified except for the flange portion 13.

The hat-shaped channel member is usually formed by drawing (drawing) or bending (foaming), and the U-shaped channel member is bending.
FIG. 2 is an explanatory view of the drawing of the hat-shaped channel member, and the blank (base plate) B placed on the horizontal wall forming portion of the punch 31 is positioned on the horizontal wall forming portion of the punch 31 by the pad 32. And is held between the lower surface of the die 33 and the blank holder 34. Then, by moving the die 33 downward against the pressing force of the blank holder 34, the vertical wall portion is formed by the cooperation of the punch 31 and the die 33, and a hat shape is formed at the end of forming (bottom dead center). Molded into a channel shape. In the figure, the radius of curvature of the bending portion (also referred to as “die shoulder”) that shifts from the vertical wall forming portion of the die 33 to the lower surface is approximately rd, and also from the vertical wall forming portion of the punch 31 to the horizontal wall forming portion. The radius of curvature of the bending portion (also referred to as “punch shoulder”) to be set is generally set to rp. The same applies to FIGS. 3 and 4 below.
FIG. 3 is an explanatory view of the bend forming of the hat-shaped channel member, and the position of the blank B placed on the side wall forming portion of the punch 31 is not shifted by the pad 32 on the side wall forming portion of the punch 31. The vertical wall portion is formed by the cooperation of the punch 31 and the die 33, and the bottom surface of the die 33 and the flange forming portion 35 are formed at the end of molding (bottom dead center). By forming a flange portion with a blank end portion interposed therebetween, a hat-shaped channel shape is formed.
FIG. 4 is an explanatory view of the bending of the U-shaped channel member, and the position of the blank B placed on the lateral wall molding portion of the punch 31 is shifted on the lateral wall molding portion of the punch 31 by the pad 32. The vertical wall portion is formed by the cooperation of the punch 31 and the die 33 by moving the die 33 downward, and is formed into a U-shaped channel shape at the end of forming.

  2 to 4, the punch 31 is disposed below the die 33 at the top dead center of the press, and the blank is formed by moving the die 33 toward the punch 31 in the molding process. In contrast, there is a case where the punch 31 is arranged above the die 33 and the die is raised to the punch side during the forming process. In the illustrated example, the punch is the fixed side and the die is the moving side. Conversely, the die may be the fixed side and the punch may be the moving side.

  The cross-sectional shape shown in FIG. 1 is a target shape, and when the cross-sectional center line of the channel member (a line connecting the centers of the vertical cross-sections) is a straight line, the hat-shaped channel member can be drawn or bent. In this molding, the vertical wall portion 12 is subjected to bending and bending back deformation, so that tensile and compressive stress distribution is generated on the front and back surfaces of the vertical wall portion 12, and after the mold release, the stress is released and elastic recovery (spring As shown in FIG. 5, a wall warp in which the outside of the vertical wall portion 12 is recessed occurs. However, since the draw forming has a large bending and bending back deformation compared to the bending forming, the warpage is also large. In the case of bending the U-shaped channel member, no stress distribution is generated in the vertical wall portion, so that the vertical wall portion is not warped.

As described above, in the straight hat-shaped channel member, the vertical wall portion 12 is warped. As wall warp suppressing means for suppressing this, for example, the following techniques are known.
(1) Formation of a frozen bead (Non-patent Document 1: The 54th Plastic Working Joint Lecture 109T, Lectures p17-18)
In order to increase the rigidity of the vertical wall portion, the shape freezing bead (unevenness having ribs in the vertical direction) is formed to reduce and suppress wall warpage.
(2) BHF (Blank Holding Force) control at the end of molding This is a method to control the tension of the vertical wall at the end of molding. Apply tension to eliminate the stress difference on the back of the wall thickness of the vertical wall.
(3) Formation of coining beads (Patent Document 1: Japanese Patent Laid-Open No. 2001-87816)
In order to reduce the compressive force generated in the vertical wall, a coining bead (linear recess) is pressed (coined) on the vertical wall during molding or in the finishing process to reduce or eliminate the stress difference in the thickness direction. .
54th Plastic Working Joint Lecture 109T, Lectures p17-18 JP 2001-87816 A

  However, in the case of a channel member having a curved cross-sectional center line, not only the cross-sectional shape is a hat-shaped channel but also a U-shaped channel, not only the vertical wall portion is warped but also the member is twisted (twisted). It becomes like this. FIG. 6 shows the twisted state of the curved hat-shaped channel member 1 after the molding is finished and released, and FIG. 6 (1) shows the lateral wall portion 11 on the upper side and the flange portions 13 and 13 on the lower side. 6 (2) is a cross-sectional view taken along line AA of FIG. 6 (1), the solid line indicates the shape of the member after molding, and the two-dot chain line indicates the target shape. Also in the case of a curved channel member, the cross-sectional shape thereof is the same as in FIG. 1, but since the member is curved, it is necessary to distinguish between the radially inner side and the outer side of each component part of the member. In some cases, at the end of the reference numeral in FIG. 1, the inner part is marked with a lowercase letter “i” and the outer part is marked with “o”. For example, the inner vertical wall portion is indicated by 12i, and the outer vertical wall portion is indicated by 12o.

FIG. 6 is a perspective view of the member in a four-point support state in which both ends in the radial direction of the lateral wall portion 11 are constrained on the same plane (horizontal plane) at each circumferential end portion of the curved hat-shaped channel member 1. A twisted state is shown, and a circle in the figure indicates a restraint point. Hereinafter, when the twist of the member is described, the four-point support state is assumed.
Here, the direction of twist is defined as follows. As shown in the figure, the direction of torsion when the outer vertical wall portion 12o or the outer flange portion 13o is inclined toward the horizontal wall portion 11 is defined as "positive", and the opposite case is defined as "negative". Is defined as the “torsion angle”.

In the formation of the curved channel member, the main cause is the warp of the vertical wall caused by the stress difference between the thickness and the back of the vertical wall (Inoue et al., 53rd Joint Seminar on Plastic Processing) (2002), 271) and the theory mainly caused by in-plane stress (elongation and shrinkage) of the flange part and the vertical wall part (edited by the Technical Committee on Thin Steel Sheet Forming, Handbook for Press Forming Difficulty, (1987), 177, Issued by Nikkan Kogyo Shimbun), but the cause of twisting is not always clear.
The present invention has been made in view of such problems, and an object of the present invention is to provide a method for forming a curved channel member that can reduce and suppress twisting of the member.

  The inventor has formed a curved channel member by changing the pressing force of the pad in various ways, and found that when the blank is not pressed, the twist is unlikely to occur, and as a result of pursuing the cause, In the upper part of the vertical wall part of the curved channel member molded and held in the target shape of the curved channel member in the mold, tensile stress is generated inside the plate thickness along the height direction, and compressive stress is generated outside. It has been found that when the mold is released, these stresses are released and the member is deformed so as not to twist. Further, the present inventors have examined whether the portion of the curved channel member in the curved circumferential direction can be effectively reduced and suppressed by preventing the pad from being pressed. The present invention has been completed based on such findings and examination results.

  That is, according to the first method for forming a curved channel member of the present invention, a curved channel member in which a vertical wall portion is formed on both sides of the horizontal wall portion via a bent portion and the center line of the cross section is curved is a target to be molded. A method of forming a curved channel member, wherein the curved channel member is formed and held in a target shape in the molding die at the end of molding, and is directed from the end of the curved channel member toward the center in the circumferential direction of the curve. When the region up to about ¼ of the member length along the center line of the cross section is called a ¼ region, at least in the ¼ region on both ends of the curved channel member, A torsion suppressing portion in which tensile stress is present on the inner side and compressive stress is present on the outer side along the height direction is formed.

  The molding method according to the first aspect of the present invention has a configuration corresponding to each part of the curved channel member, and the inner width between the vertical wall portions is the curved shape at least in the region corresponding to the ¼ region on both ends. A curved channel intermediate member having a large portion larger than the target inner width between the vertical wall portions of the channel member is molded, and at the end of molding, bending on both sides of the lateral wall portion existing in the large portion of the curved channel intermediate member is performed. By forming the portion so as to be a part of each of the vertical wall portions of the curved channel member, a twist suppressing portion can be formed on the upper portion of the vertical wall portion.

  In the molding method according to the first aspect of the present invention, a structure corresponding to each part of the curved channel member is provided, and the bending portion is bent in the curved channel member at least in a region corresponding to the ¼ region on both ends. A curved channel intermediate member having a large-diameter bending portion larger than a target curvature radius of the portion is formed, and at the end of molding, a part of the large-diameter bending portion of the curved channel intermediate member is the curved channel member Thus, the torsion suppressing portion can be formed on the upper portion of the vertical wall portion.

In the molding method of the first invention, a punch having a lateral wall molding part for molding the lateral wall part of the curved channel member, and a die for molding the vertical wall part in cooperation with the punch are prepared, A blank is pressed on the lateral wall forming part of the punch corresponding to the central part of the curved channel member in the circumferential direction of the punch, and a structure corresponding to each part of the curved channel member is provided. In a region corresponding to the region, the curved wall intermediate member formed into an arched lateral wall portion formed in an arch shape with a gap between the lateral wall portion and the lateral wall molded portion of the punch is molded. The arched lateral wall portion of the curved channel intermediate member can be formed to be the lateral wall portion and the bent portion of the curved channel member, whereby the upper portion of the vertical wall portion It is possible to form the suppressed portion Gillet.
According to this molding method, the blank is pressed against a portion that is not very effective in suppressing twisting, a gap is formed at least in a ¼ region where the twisting suppressing effect is high, and an arch-shaped lateral wall in which a gap is formed at the end of molding Since the portion is pressed down to form the lateral wall portion and the bent portion of the curved channel member, at least a quarter region on both end sides of the curved channel member while preventing displacement of the blank with respect to the molding die during molding. The twist suppressing portion can be formed on the upper portion of the vertical wall portion, and the twist of the curved channel member can be effectively suppressed and reduced.

  In forming the gap, the punch is provided with a gap forming means for forming a gap between the lateral wall forming part of the punch and the lateral wall part of the curved channel intermediate member, and the gap forming means A gap can be formed between the lateral wall portion. Thereby, a clearance gap can be stably formed in a predetermined area | region, and it can pull and can suppress the twist suppression shaping | molding.

  Further, in the second method for forming a curved channel member of the present invention, the vertical wall part is formed on both sides of the horizontal wall part via the bent part, and the curved channel part and the cross-sectional center line having a curved cross-sectional center line are straight lines. A method of forming a curved channel member for which a curved channel member in which a straight channel portion is coupled is formed, and the curved channel member is molded and held in a target shape in a molding die at the end of molding. In this state, in at least the straight channel portion of the curved channel member, a torsion suppressing portion having tensile stress inside and compressive stress inside along the height direction is formed on the upper portion of the vertical wall portion.

  In the molding method according to the second aspect of the present invention, a configuration corresponding to each part of the curved channel member is provided, and an inner width between the vertical wall parts is a target between the vertical wall parts of the curved channel member at least in the straight channel part. The curved channel intermediate member having a large portion larger than the inner width is formed, and at the end of molding, the bent portions on both sides of the lateral wall portion existing in the large portion of the curved channel intermediate member are both of the curved channel members. It can shape | mold so that it may become each part of a vertical wall part, and, thereby, the said twist suppression part can be shape | molded by the upper part of the said vertical wall part.

  The molding method according to the second aspect of the present invention includes a configuration corresponding to each part of the curved channel member, and at least in the straight channel part, the bending part has a larger diameter than the target curvature radius of the bending part of the curved channel member. The curved channel intermediate member formed as a bent portion is molded, and at the end of molding, a part of the large-diameter bent portion of the curved channel intermediate member becomes a part of the vertical wall portion of the curved channel member. Thus, the twist suppressing portion can be formed on the upper portion of the vertical wall portion.

In the molding method according to the second aspect of the present invention, a punch having a lateral wall molding part for molding the lateral wall part of the curved channel member, and a die for molding the vertical wall part in cooperation with the punch are prepared, and the bending is performed. A blank is pressed on the horizontal wall forming part of the punch corresponding to the central part of the curved channel member in the circumferential direction of the punch, and has a configuration corresponding to each part of the curved channel member. A curved channel intermediate member formed into an arch-shaped lateral wall portion formed in an arch shape with a gap between the punched lateral wall molding portion and the arch-shaped lateral wall of the curved channel intermediate member is formed at the end of molding. The portion can be formed to be the lateral wall portion and the bent portion of the curved channel member, thereby forming the twist suppressing portion on the upper portion of the vertical wall portion. Door can be.
According to this molding method, even in the case of a curved channel member having a complicated shape in which the center line of the cross section is a combination of a straight line and a curve, the blank is pressed against a portion that is not very effective in suppressing twisting, and at least the twisting suppressing effect is achieved. Since the arch-shaped lateral wall portion is formed in the straight channel portion having a high height and the arch-shaped lateral wall portion is crushed at the end of molding to form the lateral wall portion and the bent portion of the curved channel member, While preventing the displacement with respect to the mold, the twist suppressing portion can be formed on the upper portion of the vertical wall portion existing in at least the straight channel portion of the curved channel member, and the twisting of the member can be effectively suppressed and reduced. .

  Also in this forming method, when forming the gap, the punch is provided with a gap forming means for forming a gap between the horizontal wall forming portion of the punch and the horizontal wall portion of the curved channel intermediate member, and the gap forming means A gap can be formed between the lateral wall forming portion of the punch and the lateral wall portion of the curved channel intermediate member.

  Further, the third curved channel member molding method of the present invention is a curved channel member comprising a curved channel portion in which a vertical wall portion is formed on both sides of a lateral wall portion via a bent portion, and a cross-sectional center line is curved, Alternatively, it is a method for forming a curved channel member in which a curved channel member in which a straight channel portion having a straight section center line is coupled to the curved channel portion is formed, and is curved in the molding die at the end of molding. In the state in which the channel member is molded and held in the target shape, tensile stress is internally present along the height direction and compressive stress is present outside the upper portion of the outer vertical wall portion on the outer side of the curved radial direction of the curved channel member. The torsion suppressing portion to be molded is formed.

  In the molding method according to the third aspect of the present invention, a structure corresponding to each part of the curved channel member is provided, and the inner vertical wall portion and the bent part inside the curved radial direction are the target shape of the same part of the curved channel member. And the inner width between the inner vertical wall portion and the outer vertical wall portion on the outer side in the radius direction is a larger portion than the target inner width between the two vertical wall portions of the curved channel member. The curved channel intermediate member is molded, and at the end of molding, the bent portion on the outer vertical wall portion side existing in the large portion of the curved channel intermediate member becomes a part of the outer vertical wall portion of the curved channel member. Thus, the twist suppressing portion can be formed on the upper portion of the outer vertical wall portion.

  In the molding method according to the third aspect of the present invention, a structure corresponding to each part of the curved channel member is provided, and the inner vertical wall part and the bent part inside the curved radial direction are the targets of the same part of the curved channel member. The inner width between the inner vertical wall portion and the outer vertical wall portion on the outer side in the curved radial direction is equal to the target inner width between the two vertical wall portions of the curved channel member, and the outer vertical wall. The curved channel intermediate member is formed with a large-diameter bent portion whose bent portion on the side is larger than the target radius of curvature of the bent portion of the curved channel member, and at the end of molding, the large diameter of the curved channel intermediate member A part of the bent part can be formed to be a part of the vertical wall part of the curved channel member, whereby the twist suppressing part can be formed on the upper part of the vertical wall part.

  According to the molding method of the present invention, when the curved channel member is press-molded, at the end of molding, on the upper part of the vertical wall portion in the region having a large effect in suppressing the twist of the curved channel member in the height direction. Since the torsion suppressing portion in which the tensile stress is present inside and the compressive stress is present outside is formed, the twist of the curved channel member after the mold release is effectively suppressed and reduced.

First, the forming of the curved channel member will be briefly described. FIG. 7 shows a member after drawing of the curved hat-shaped channel member 1 corresponding to FIG. 6 and a blank (indicated by a broken line) B before the forming. The curved shape of the curved hat-shaped channel member 1 includes a radius of curvature CR of the cross-sectional center line (sometimes referred to as “curved center line”) of the cross section and a central angle around the center of curvature sandwiching the curved portion (arc). It is expressed using θc.
As the blank B is molded into a hat-shaped channel shape, the blank B flows radially into the molding die along the radial direction of the curve and is molded into the curved channel member 1 as indicated by the dashed arrows. At the end of molding (bottom dead center), compressive stress is generated in the outer flange portion 13o and tensile stress is generated in the inner flange portion 13i along the circumferential direction of the curve. be called.
In the case of bending, the same shape blank is used, but as with drawing, along the circumferential direction of the curve, compressive stress is applied to the outer vertical wall and outer flange, while the inner vertical wall and inner flange are subjected to compression stress. Generates tensile stress.

In order to investigate the cause of twisting when the curved channel member is formed, the present inventor firstly calculates the channel member height (molding height) H and the twist angle θ when forming the curved channel member. When the relationship is numerically calculated by simulating the formation of a curved channel member, the hat-shaped channel member is less than about H = 20 mm, the U-shaped channel member is less than about H = 40 mm, and the twist occurs in the negative direction. It was found that it would turn in the positive direction beyond that.
As a result of further pursuing this cause, it was found that when the height of the member was increased by the following mechanisms (1) to (3), a positive twist occurred.
(1) When the height of the member increases, the wall warp of the vertical wall as shown in FIG. 5 becomes large at the time of mold release, and the opening caused by the wall warp between the flanges with respect to the target normal shape ( (Open mouth) becomes large.
(2) When a wall warp occurs in the curved channel member, it is geometrically shrunk, and tensile stress is applied in the curved circumferential direction to the vertical wall portion on the flange portion side, and tensile stress is applied to the vertical wall portion on the extended flange portion side in the curved circumferential direction. Compressive stress acts, and the magnitude of these stresses increases toward the lower portion (flange portion side) of the vertical wall portion.
(3) In order to relieve these tensile stress and compressive stress, the entire member is twisted in the positive direction as shown in FIG.

  On the other hand, the inventor discovered that, when bending the curved hat-shaped channel member, when the pressing of the blank by the pad was stopped, misalignment was likely to occur, but twisting was difficult to occur. FIG. 8 shows a transverse cross-sectional view of a curved hat-shaped channel member that is bent by releasing the pad. As shown in FIG. 8, the lower portion of the bent portion 14 on the side of the horizontal wall portion 11 of the vertical wall portion 12 is shown. Then, a convex warp is formed on the outer side, and a convex warp is formed on the inner side in the upper portion of the bent portion 15 on the flange portion 13 side. When molded into such a shape, large tensile and compressive stresses in the circumferential direction generated in the lower part of the vertical wall described in (2) above are geometrically relaxed, so that twisting of the member is suppressed. It is estimated that

  The reason why the shape is as shown in FIG. 8 when the blank is not pressed by the pad will be described below. FIG. 9 shows the molded state of the curved channel intermediate member 1a in the middle of molding when the curved hat-shaped channel member is bent from the blank by releasing the pad. The curved channel intermediate member 1a includes an arch-shaped lateral wall portion 11ah formed on the lateral wall forming portion 41 of the punch 31 via a gap S, and the longitudinal wall portion 12a and the curved hat-shaped channel member 1 are formed on both sides thereof. A bent flange portion 13a corresponding to the bent portion 15 and the flange portion 13 is formed. Further, the die 33 is lowered from the vicinity of the bottom dead center to the bottom dead center, and when the molding is completed, the arch-shaped lateral wall portion 11ah is pressed down flat by the lateral wall molding portion 41 of the punch 31 by the pad 32. FIG. 10 shows the curved hat-shaped channel member 1 in the molding die at the end of molding, which is molded and held in the same shape as the target shape. The arch-shaped lateral wall portion 11ah of the curved channel intermediate member 1a forms the lateral wall portion 11 and the bent portion 14 of the curved hat-shaped channel member 1, and the curved channel intermediate portion bent at the punch shoulder (radius rp). The bent portion 14a of the member 1a is bent back straight along the wall surface of the vertical wall forming portion of the punch 31 to form the twist suppressing portion R on the upper portion of the vertical wall portion 12 of the curved hat-shaped channel member 1. In the torsion suppressing portion R, by bending back the bending portion 14a, along the height direction of the vertical wall portion 12, a tensile stress is generated inside the plate thickness and a compressive stress is generated outside. Occurs. When the mold is released, the stress (in other words, M) constrained by the molding die is released, and an outwardly convex warp is formed on the upper portion of the vertical wall portion 12 as shown in FIG.

  As described above, by forming the blank without pressing the blank, it is possible to suppress the twist of the curved channel member, but the blank is likely to be displaced relative to the molding die. Therefore, in order to achieve both suppression of torsion and prevention of displacement, it is only necessary to prevent the blank from being pressed at a portion having a large influence on the twist of the member and to press the blank at a portion having a small influence.

  Then, the site | part effective in suppression of a twist was investigated with the following method. In this technique, when a curved hat-shaped channel member is drawn, a change in the twist angle is examined by suppressing wall warpage, which is a cause of twist, at various sites. In drawing, twisting appears larger than when bending a curved hat-shaped channel member, so this is a preferred form for examining the site affected by twisting.

A cold rolled steel sheet having a thickness of 1.2 mm and a strength of 590 MPa is used as a blank, the radius of curvature CR of the cross-sectional center line is 1000 mm, the central angle θc of the curved portion is 32 °, the member height H is 40 mm, the member width W is 60 mm, and the flange The hat-shaped channel member having the width Lf = 35 mm of the portion and the radius rp = rd = 5 mm of the bent portion is formed by drawing, and is formed with respect to the curved hat-shaped channel member 1 as shown in FIG. Wall warpage does not occur in the outer vertical wall portion 12o and the inner vertical wall portion 12i of the portion (the portion 1 to 6 in the figure) of the curved length (or θc) from both ends, the center portion, and the end portion. In addition, a constraint with a width of 40 mm was given in the circumferential direction, and the twist angle after molding was calculated using a general-purpose FEM (finite element method). FIG. 12 shows a graph obtained by organizing the relationship between the torsion angle and the constrained portion obtained by calculation. In addition, the torsion angle when not restrained is 5.3 °.
From FIG. 12, it can be seen that when restraint at one place is given, the effect of suppressing twisting is large in the order of the parts 1, 5 and 2. When two restraints are applied, the effect is greater in the order of parts 2 and 5, 1 and 4, and when parts 2 and 5 are constrained, the twist is about half that of the unconstrained part. It can be seen that the twist is reduced to about ¼ when constraints are applied to 1, 2, 4, and 5.

From the above survey results, the following became clear. As shown in FIG. 13, when the curved hat-shaped channel member 1 is formed (drawing or bending), in the circumferential direction of the curvature, a twist prevention measure is applied to each quarter region Q on both ends of the member. It is most effective to take. The quarter region Q is a region that is ¼ to almost ¼ of the member length (or θc) along the curved center line from the end of the member.
Therefore, in order to suppress or prevent the twist of the curved channel member, at the end of molding, preferably at the upper part of the vertical wall portion of the curved channel member existing in at least the quarter region Q on both ends of the curved channel member. As shown in FIG. 10, a torsion suppressing portion R in which tensile stress is generated inside the plate thickness and compressive stress is generated outside is formed in the region directly below the bent portion at both ends of the lateral wall portion.

Hereinafter, a method for forming a curved channel member capable of forming such a twist suppressing portion will be described more specifically.
First, as described above, the method for forming a curved hat-shaped channel member according to the first embodiment has a shape corresponding to the curved hat-shaped channel member 1 having a target shape, as shown in FIG. Bending the curved channel intermediate member 1a having the arch-shaped lateral wall portion 11ah, and continuing the molding as it is, as shown in FIG. A lateral wall portion and a bent portion of a curved channel member are formed.
As described above, the region where the arch-shaped lateral wall portion is to be formed is a region corresponding to at least a quarter region on both ends of the member. In this region, a blank is formed as shown in FIG. On the other hand, since the effect of preventing twisting is small at the central portion in the curved circumferential direction (portions corresponding to the portions 3 and 6 in FIG. 11), if the blank is pressed at this portion Good. The curved channel intermediate member having the arched lateral wall portion may be formed by drawing.

  The blank is held at the portion corresponding to the central portion of the curved hat-shaped channel member 1 in the circumferential direction of the curve, and at least at the region including the ¼ region, the blank is not pressed from the initial stage to the middle stage. In order to press the arch-shaped lateral wall portion 11ah formed through the gap S against the lateral wall molding portion of the punch by the pad 32 and form it into a flat shape, the pad 32 is divided into structures, and the pad is pressed at the central portion and other portions. What is necessary is just to set it as the structure which can control a pressure separately. Further, as a method of forming the arch-shaped lateral wall portion 11ah into a flat shape, a pad is provided in a molding die corresponding to the central portion of the curved hat-shaped channel member 1, and a pad is not provided in other regions. As shown in FIG. 14, the die 33 is provided with a lateral wall molding portion 42 for molding the arch-shaped lateral wall portion 11ah into a flat shape in cooperation with the lateral wall molding portion 41 of the punch 31, and the punch 31, die 33, and flange molding portion 35 are provided. And may be molded by

Further, as shown in FIG. 15, a gap forming means 51 for forcibly forming the gap S can be provided in the punch 31. By providing the gap forming means 51, the gap between the punch 31 and the arch-shaped lateral wall portion 11ah can be stably formed, and the molding is more stable.
The gap forming means 51 includes an elevating column 52 whose tip is raised and lowered from the horizontal wall forming portion 41 of the punch 31 and a fluid pressure cylinder 53 that elevates and lowers the elevating column 52. As the fluid pressure, gas pressure is generally used, but hydraulic pressure may be used.
The gap forming means 51 is used as follows. The raising / lowering column 52 is raised halfway through the molding to forcibly form a gap S between the punch 31 and the blank, thereby forming the arch-shaped lateral wall portion 11a. The elevating column 52 is lowered so that the front end portion of 52 is accommodated inside the horizontal wall forming portion 41 of the punch 31, and the arched horizontal wall portion 11 a is flattened by the horizontal wall forming portion 42 provided on the pad 32 or the die 33. Mold.

  The gap forming means 51 is configured to move the elevating column 52 up and down by the fluid pressure cylinder 53, but is not limited thereto, and may be an elastic member such as a spring, for example. In this case, at the end of molding, the elevating column 52 is pushed down together with the arched lateral wall portion 11a by the lateral wall molding portion 42 of the pad 32 or the die 33.

  Next, the twist suppression molding method according to the second embodiment will be described. In the second embodiment, first, in the intermediate molding step, as shown by reference numeral 1a in FIG. 16, the lateral wall portion 11a, the bent portions 14a and 15a, the outer side corresponding to the respective portions of the curved hat-shaped channel member to be molded. In addition, the curved channel intermediate member 1a having the inner vertical wall portion 12a and the outer and inner flange portions 13a and having a laterally symmetrical shape is bent or drawn.

  At both ends of the curved channel intermediate member 1a, at least in the region corresponding to the quarter region of the curved hat-shaped channel member, the inner width between the vertical wall portions 12a and 12a is as shown in FIG. A large portion having an inner width larger by 2 × ΔW than the target inner width W of the curved hat-shaped channel member is formed. In the curved channel intermediate member 1a, the bent portions 14a and 15a and the flange portion 13a have the same dimensional shape as the target shape of the curved hat channel member with respect to the curved hat channel member to be molded. Therefore, the horizontal wall portion 11a is longer by 2ΔW, and both the vertical wall portions 12a are shorter by ΔW. In addition, the curved channel intermediate member 1a in the figure shows a target shape.

  Then, as shown in FIG. 16, in the finish forming step, the both end portions of the lateral wall portion 11a are bent and formed by a forming die having a punch 31 and a die 33 for forming a curved hat-shaped channel member having a target shape. Then, as shown in FIG. 10, the bent portions 14a on both sides of the lateral wall portion 11a are bent back into a flat shape at the end of molding, and the vertical wall portions 12 on both sides of the curved hat-shaped channel member 1 molded into the target shape. A twist suppressing portion R is formed on the top. Thereby, in the upper part of the vertical wall portions 12 on both sides, tensile stress is generated on the inner side of the plate thickness and compressive stress is generated on the outer side. When the mold is released, the stress is released and the member is deformed as shown in FIG. The twisting of the member is suppressed and reduced. Hereinafter, such finish molding is referred to as bending back bending molding.

  Here, a calculation example of the twist angle of the member when the bent portion of the bent channel intermediate member 1a shown in FIG. A cold rolled steel sheet having a thickness of 1.2 mm and a strength of 590 MPa is used as a blank, the radius of curvature CR of the cross section center line is 1000 mm, the central angle θc of the curved portion is 32 °, the member height H is 40 mm, the member width W is 60 mm, A hat-shaped channel member having a width Lf of 35 mm and a radius rp = rd = 5 mm of a bent portion is an object to be molded, and a large portion (vertical wall portion) is formed in various regions in the intermediate molding process (drawing) at the time of finish molding. An intermediate member was used in which the inner width between them was expanded to the inner side and the outer side by ΔW = 2 mm. As an intermediate member, one having a large portion formed in the entire length in the circumferential direction (intermediate member A), one having a large portion formed in a quarter region on both ends of the member (intermediate member B), 1 / Three types were assumed (intermediate member C) in which a large portion was formed in the central portion, which is a half of the member length along the cross-sectional center line, excluding the four regions. And the twist angle of the curved hat-shaped channel member after the bending back molding of the bending part was calculated using FEM. The calculation results were intermediate member A: twist angle 1.0 °, intermediate member B: twist angle 2.5 °, and intermediate member C: 3.6 °. In the conventional drawing without using the intermediate member, the twist angle is 5.3 °.

Furthermore, another embodiment (third embodiment) of the twist preventing molding method will be described.
In the third embodiment, first, in the intermediate molding step, as shown by reference numeral 1a in FIG. 17, the lateral wall portion 11a, the bent portions 14a and 15a, the outer side corresponding to the respective portions of the curved hat-shaped channel member to be molded. In addition, a curved channel intermediate member 1a having an inner vertical wall portion 12a and outer and inner flange portions 13a and having a laterally symmetric shape in cross section is drawn or bent.

  At both ends of the curved channel intermediate member 1a, at least in a region corresponding to a quarter region of the curved channel member, the radius of curvature rpa of the bent portion 14a is a curved hat-shaped channel as shown in FIG. A large-diameter portion having a radius larger than the target curvature radius rp of the bending portion 14 of the member is used. In the curved channel intermediate member 1a, the inner width between the vertical wall portions 12a, the dimensional shape of the flange portion 13a, and the bent portion 15 are the same as the target dimensional shape of the corresponding portion of the curved hat-shaped channel member to be molded. The horizontal wall portion 11a and the vertical wall portions 12a are slightly shorter than the target shape. In addition, the curved channel intermediate member 1a in the figure shows a target shape.

  Then, in the finish forming step, as shown in FIG. 17, the horizontal wall portion 11a and the bent portion 14a are bent by a forming die having a punch 31 and a die 33 for forming a curved hat-shaped channel member having a target shape. When forming so as to have the target shape of the shaped hat-shaped channel member, as shown in FIG. 10, the lateral wall portion 11a of the curved hat-shaped channel member 1 having the desired shape is formed into the lateral wall portion 11a and the large-diameter bent portion 14a. In addition to forming the bent portion 14, a part of the bent portion 14 is bent back into a flat shape to form a twist suppressing portion R on the upper portion of the vertical wall portion 12. As a result, a tensile stress is generated on the inside of the plate thickness and a compressive stress is generated on the outside of the upper portion. When the mold is released, the stress is released and the member is deformed as shown in FIG. Is done. Hereinafter, this finish molding is referred to as partial bending back molding of a large-diameter bending portion.

  Here, a calculation example of a twist angle of a member when a large-diameter bent part is partially bent back using the curved channel intermediate member 1a shown in FIG. A cold rolled steel sheet having a thickness of 1.2 mm and a strength of 590 MPa is used as a blank, the radius of curvature CR of the cross section center line is 1000 mm, the central angle θc of the curved portion is 32 °, the member height H is 40 mm, the member width W is 60 mm, A hat-shaped channel member having a width Lf of 35 mm and a radius rp = rd = 5 mm of a bent portion is a molding target. An intermediate member formed with a curvature radius of 14a = 8 mm) was used. As an intermediate member, one having a large diameter portion formed in the entire length in the circumferential direction (intermediate member A), one having a large diameter portion formed in a quarter region on both end sides of the member (intermediate member B), Three types of intermediate members (intermediate member C) in which a large-diameter portion is formed in the central portion, which is a half of the member length along the cross-sectional center line, excluding the 1/4 region, were assumed. Then, the twist angle of the curved channel member after partially bending back the large-diameter bending portion was calculated using FEM. The calculation results were intermediate member A: twist angle 1.9 °, intermediate member B: twist angle 3.2 °, and intermediate member C: 3.9 °.

  The embodiment of the method for forming a curved hat-shaped channel member that is curved as a whole has been described above. Next, a curved shape in which a curved channel portion having a curved center line and a straight linear channel portion are coupled. A method for forming a channel member (such a member may be referred to as a “composite curved channel member”) will be described. As the compound curved channel member, as shown in FIG. 18, a compound curved channel member 21 in which straight channel portions SP, SP are coupled to both sides of the curved channel portion CP can be exemplified.

  As is clear from the investigation results shown in FIG. 12, since the wall warp of the vertical wall portion appears larger at the end portion of the curved channel member than at the center portion, suppressing the warpage of this portion is to suppress the twist. It is effective. As shown in FIG. 18, when the straight channel portions SP and SP are coupled to both sides of the curved channel portion CP, the wall warp of the straight channel portions SP and SP promotes the wall warp at the end of the curved channel portion CP. As a result, the twist appears greatly. On the other hand, if the wall warp of the straight channel portions SP, SP is suppressed, the wall warp at the end of the curved channel portion CP can also be suppressed.

  For this reason, in order to effectively suppress the twist of the compound curved channel member as shown in FIG. 18, the blank is pressed on the lateral wall forming portion of the punch corresponding to the curved central portion of the curved channel portion CP. The blank is not formed on the side wall forming portion of the punch corresponding to the straight channel portion SP, and a gap is formed on the punch corresponding to the straight channel portion SP as shown in FIG. It is effective to form the curved channel intermediate member 1a having the arch-shaped lateral wall portion 11ah, and subsequently form the arch-shaped lateral wall portion 11ah into a flat shape at the end of the molding. Of course, the blank is pressed on the side wall forming portion of the punch corresponding to the central portion of the curved channel portion CP, and the blank portion is formed so as not to be pressed in a region including at least a quarter region of the curved channel portion CP. Thus, twist can be further suppressed. Furthermore, by providing the gap forming means 51, it is possible to stably form the arched lateral wall portion through the gap, and the molding is stabilized. In the case of drawing, it is desirable to provide the gap forming means 51.

In the formation of the compound curved hat-shaped channel member 21 shown in FIG. 18, when a blank is pressed on a punch corresponding to all of the curved channel portion CP and the straight channel portions SP and SP, bending or drawing, or curved The torsion angle was calculated using FEM when the blank was pressed on the punch corresponding to the central portion of the channel portion CP and bending or drawing was performed without pressing the blank in other regions. In the calculation of the torsion angle, the member is supported in a state where the four corners are constrained in the four-point support state.
The compound curved channel member to be calculated is a cold-rolled steel plate having a thickness of 1.2 mm and a strength of 590 MPa formed as a blank, and the shape of the curved channel portion CP has a radius of curvature CR of the cross-sectional center line CR = 1000 mm, The central angle θc = 14.4 ° of the bending portion, the member height H = 81.2 mm, the member width W = 100 mm, the flange portion width Lf = 26.2 mm, the bending portion radius rp = rd = 5 mm, and a straight line The channel portions SP and SP are each 200 mm in length (see FIGS. 1 and 18). Further, the pressing force of the pad in bending molding and drawing was 30 tons, and the pressing force of the blank holder in drawing was 60 tons.
As a result, when the blank is pressed on the punches corresponding to all of the curved channel portion CP and the straight channel portions SP, SP and bent (normally formed), the twist angle θ at the center in the circumferential direction of the member is 4. It was 3 °. On the other hand, when the blank was pressed on the punch corresponding to the central portion of the curved channel portion CP and bending was performed without pressing the blank in other regions, the twist angle was 0.3 °. On the other hand, when the blank is pressed against all the regions of the composite curved channel member and drawn (normally molded), the twist angle is 6.2 °, and the punch corresponding to only the central portion of the curved channel portion CP. When the blank was pressed up and drawn and bent without pressing the blank in other areas, the twist angle was 4.7 °.

  As described above, in the formation of the compound curved channel member, the curved channel intermediate member in which the arch-shaped lateral wall portion is formed at least in the straight channel portion via the gap is molded, and this is molded into the target shape at the end of molding. It is a torsional restraint with tensile stress inside the plate thickness along the height direction and compressive stress outside on the upper part of the vertical wall of the compound curved channel member molded to the target shape in the mold. This is because the portion R is formed. Therefore, also in the case of the composite curved channel member, as in FIGS. 16 and 17, first, in the intermediate molding process, the composite curved channel intermediate member in which a large portion or a large diameter portion is formed at least in the straight channel portion is formed ( Next, the composite curved channel member of the target shape is formed using these intermediate members, and then the tensile stress is applied to the inside of the plate thickness along the height direction at the upper part of the vertical wall portion. , A compressive stress can be formed on the outer side, thereby suppressing or reducing twisting of the member.

Furthermore, a molding method in which twist suppressing means is applied to a region other than the ¼ region of the curved channel member and the straight channel portion of the composite curved channel member will be described.
According to FIG. 12, with respect to the radial direction of the curve, it is understood from the comparison between the parts 1 and 2 and the parts 4 and 5 that the effect of suppressing the twist is higher when the outer vertical wall part 12o is constrained than the inner vertical wall part 12i. . Accordingly, a curved channel member composed only of the curved channel portion, a composite curved channel member in which the curved channel portion and the straight channel portion are coupled (hereinafter referred to as “curved channel member” without distinguishing between the two). In any case, the height of the curved channel member formed and held in the molding die at the end of molding is set in the height direction on the upper side of the outer vertical wall portion (the outer vertical wall portion existing in all regions in the circumferential direction). It can be seen that twisting of the member is suppressed or reduced by forming a tensile stress inside the plate thickness and forming a compressive stress outside. Hereinafter, specific embodiments of the molding method will be described with reference to the drawings.

  First, the twist prevention molding method of the fourth embodiment will be described. In this embodiment, first, in the intermediate forming step, as shown by reference numeral 1a in FIG. 19, the horizontal wall portion 11a, the bent portions 14ai and 14ao, the outer vertical wall portions corresponding to the respective portions of the curved channel member to be formed. The curved channel intermediate member 1a having 12ao, the inner vertical wall portion 12ai, the outer flange portion 13ao, and the inner flange portion 13ai is formed (drawn or bent).

  As shown in the figure, the inner width between the vertical wall portions 12ao and 12ai is ΔW with respect to the target inner width W of the curved channel member over the entire length of the cross-sectional center line of the curved channel intermediate member 1a. A large portion having a large inner width is formed. The curved channel intermediate member 1a has dimensions of the inner and outer flange portions 13ai and 13ao, the inner and outer bent portions 15ai and 15ao on the flange side, and the inner vertical wall portion 12ai with respect to the curved channel member to be molded. Is formed to be equal to the target size and shape of the curved channel member, so that the horizontal wall portion 11a is longer by ΔW toward the outer vertical wall portion 12ao and the outer vertical wall portion 12ao is shorter by ΔW. . In addition, the curved channel intermediate member 1a in the figure shows a target shape. Further, as shown in FIG. 19, the formation of a large portion by setting ΔW on the outer vertical wall portion 12ao side is referred to as “forming a large portion on the outer side”, on the contrary, on the inner vertical wall portion 12ai side. The fact that a large portion is formed by setting ΔW to “a large portion is formed on the inside” is called.

  Then, as shown in FIG. 19, the curved channel intermediate member 1a is formed into the target shape of the curved channel member by a molding die having a punch 31 and a die 33 for molding the curved channel member in the finish molding step. When the molding is performed, the curved channel member held by the molding die at the end of molding is bent back into a flat shape at the end of molding, as shown in FIG. When the torsion suppressing portion R is formed at the upper portion of the outer vertical wall portion 12o of 1 and the mold is released, the stress is released, and the torsion of the member is suppressed or reduced. Hereinafter, such molding is referred to as bending back molding of the outer bent portion.

  Here, a calculation example of the torsion angle of the member when the bent part of the outer bent portion is partially bent back using the curved channel intermediate member 1a shown in FIG. A cold-rolled steel sheet having a thickness of 1.2 mm and a strength of 590 MPa is used as a blank, and the target shape is a curvature radius CR = 1000 mm of the center line of the cross section, the central angle θc = 32 ° of the curved portion, the member height H = 40 mm, and the member width W = A curved hat-shaped channel member consisting of only a curved channel portion having a flange portion width Lf = 35 mm and a bent portion radius rp = rd = 5 mm is an object to be molded. ), An intermediate member in which a large part (in which the inner width between the vertical wall parts is extended to the outside by ΔW = 2 mm) is formed along the entire length of the center line of the cross section. As an intermediate member, over the entire length of the center line of the cross section, a large portion is formed on the outside and inside (intermediate member A), a large portion is formed only on the outside (intermediate member B), and a large portion is formed only on the inside. Three types of formed (intermediate member C) were assumed. Then, the twist angle of the curved channel member after the bending back molding of the outer bent portion was calculated using FEM. The calculation results were intermediate member A: twist angle 1.0 °, intermediate member B: twist angle 2.2 °, and intermediate member C: 3.8 °.

  Furthermore, the twist prevention molding method of 5th Embodiment is demonstrated. In this embodiment, first, in the intermediate forming step, as shown by reference numeral 1a in FIG. 20, the horizontal wall portion 11a, the bent portions 14ai and 14ao, the outer vertical wall portions corresponding to the respective portions of the curved channel member to be formed. The curved channel intermediate member 1a having 12ao, the inner vertical wall portion 12ai, the outer flange portion 13ao, and the inner flange portion 13ai is formed (drawn or bent).

  As shown in the figure, the curvature radius rpa of only the outer bent portion 14ao that connects the lateral wall portion 11a and the outer vertical wall portion 12ao extends over the entire length of the cross-sectional center line of the curved channel intermediate member 1a. A large-diameter portion that is set larger than the target radius of the bent portion 14o of the member is formed. The curved channel intermediate member 1a has dimensions of the inner and outer flange portions 13ai and 13ao, the inner and outer bent portions 15ai and 15ao on the flange side, and the inner vertical wall portion 12ai with respect to the curved channel member to be molded. Is formed to be equal to the target size and shape of the curved channel member, and therefore the lateral wall portion 11a and the outer vertical wall portion 12ao are shortened by the amount that the outer bent portion 14ao is formed larger than the target radius. In addition, the curved channel intermediate member 1a in the figure shows a target shape.

  Then, as shown in FIG. 20, the curved channel intermediate member 1a is formed into a target shape of the curved channel member by a molding die including a punch 31 and a die 33 for molding the curved channel member in the finish molding step. When the molding is finished, the curved channel member held by the molding die at the end of molding has a lateral wall portion 11a and a large-diameter outer bent portion 14ao as shown in FIG. 11 and the bent portion 14o is formed, and a part of the large-diameter bent portion 14ao is bent back into a flat shape to form a twist suppressing portion R at the upper portion of the outer vertical wall portion 12o. As a result, tensile stress is generated on the inside of the plate thickness and compressive stress is generated on the outside of the upper portion. When the mold is released, the stress is released, and the twisting of the member is suppressed or reduced. Such molding is called partial bending back molding of the outer large-diameter bending portion.

  By the way, from the examination result of the twist suppression method by the inventor, as shown in FIG. 22, in the lateral wall portion 11 of the curved channel member 1 held in the molding die at the end of molding, the bent portions 14i and 14o are formed. It was confirmed that the torsion of the member can also be suppressed and reduced by forming the torsion suppressing portion R having a tensile stress inside the plate thickness and a compressive stress inside the plate thickness. Such a stress distribution may be formed at least in the ¼ region in a curved channel member including only a curved channel portion at the end of molding, and in at least a straight channel portion in a compound curved channel member. Moreover, you may make it form only in the outer side over the full length of a cross-section centerline.

  In addition, the inventor conducted various investigations in the process of pursuing the cause of the twist of the curved channel member. As one of them, when the member height is high so as to cause a twist in the positive direction, the influence of the width of the flange portion on the twist was examined. The result is shown in FIG. From FIG. 23, it can be seen that the twist angle decreases as the width of the flange portion increases. That is, torsion can be reduced by improving the rigidity of the flange portion. FIGS. 24 (1) and 24 (2) show examples of the structure of the flange portion devised from this point of view. (1) is a bent end portion of the flange portion, and (2) is a folded end portion. Indicates The structure of these flange portions can be realized by performing processing to the extent that bending is performed at the end of molding.

FIG. 6 is a cross-sectional view of a hat-shaped and U-shaped channel member. It is a cross-sectional explanatory drawing of drawing of a hat-shaped channel member. It is a cross-sectional explanatory drawing of the bending shaping | molding of a hat-shaped channel member. It is a cross-sectional explanatory drawing of the bending process of a U-shaped channel member. It is a perspective view which shows the wall curvature state after shaping | molding of a linear hat-shaped channel member. It is the (1) top view and (2) AA sectional view taken on the line which show the twist state after shaping | molding of a curved hat-shaped channel member. It is a top view which shows the state before and behind shaping | molding of a curved hat-shaped channel member. It is a cross-sectional view of the member at the time of bending a curved hat-shaped channel member without pressing a blank. It is principal part cross-sectional explanatory drawing which shows the shaping | molding state from the shaping | molding initial stage to the middle period at the time of carrying out the bending shaping | molding of the curved hat-shaped channel member, without pressing a blank. It is principal part cross-section explanatory drawing which shows the shaping | molding state at the time of completion | finish of shaping | molding at the time of bending shaping | molding of a curved hat-shaped channel member. It is a top view which shows the restraint site | part of the vertical wall part of a curved hat-shaped channel member. It is a graph which shows the relationship between the constrained site | part and twist angle in the drawing of a curved hat-shaped channel member. It is a top view which shows the area | region which is effective in twist suppression in the case of shaping | molding of a curved hat-shaped channel member. It is principal part cross-sectional explanatory drawing which shows the bending molding state of the curved hat-shaped channel member using the die | dye which has a horizontal wall shaping | molding part. It is principal part cross-section explanatory drawing which shows the bending shaping | molding state of a curved hat-shaped channel member using the punch provided with the clearance gap formation means. It is principal part cross-sectional explanatory drawing which shows the initial state of the curved channel intermediate member concerning 2nd Embodiment, and a finishing shaping | molding process. It is principal part cross-sectional explanatory drawing which shows the initial state of the curved channel intermediate member concerning 3rd Embodiment, and a finishing shaping | molding process. It is a top view of the compound curved channel member by which the linear channel part was coupled with the both sides of the curved channel part. It is principal part cross-sectional explanatory drawing which shows the initial state of the curved channel intermediate member concerning 4th Embodiment, and a finishing shaping | molding process. It is principal part cross-sectional explanatory drawing which shows the initial state of the curved channel intermediate member concerning 5th Embodiment, and a finishing shaping | molding process. It is a principal part cross-sectional view of the curved channel member hold | maintained in the shaping | molding die at the time of completion | finish of shaping | molding concerning 4th, 5th Embodiment. It is a principal part cross-sectional view of the curved channel member hold | maintained in the shaping | molding die at the time of completion | finish of shaping | molding of another twist suppression shaping | molding. It is a graph which shows the relationship between the width | variety of a flange part, and a twist angle. It is a cross-sectional view of a curved channel member showing a structural example for increasing the rigidity of the flange portion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Curved hat-shaped channel member, 1a Curved channel intermediate member 11, 11a Horizontal wall part, 11ah Arch-shaped horizontal wall part 12, 12a Vertical wall part, 12o, 12ao Outer vertical wall part 13, 13a Flange part, 31 punch 32 pad, 33 Die 41 Horizontal wall forming part, CP Curved channel part SP Straight channel part, Q 1/4 region R Twist suppression part, S Gap

Claims (13)

A method for forming a curved channel member, in which a vertical wall portion is formed on both sides of a horizontal wall portion via a bent portion, and a curved channel member having a curved cross-sectional center line is formed.
The member length along the cross-sectional center line from the end of the curved channel member toward the center in the circumferential direction of the curve with the curved channel member formed and held in the target shape in the molding die at the end of molding. When the region up to about 1/4 of the region is referred to as 1/4 region, at least in the 1/4 region on both ends of the curved channel member, the tensile stress is inward along the height direction at the upper part of the vertical wall portion. A method for forming a curved channel member, wherein a torsion suppressing portion in which compressive stress is present outside is formed. A structure corresponding to each part of the curved channel member, and an inner width between the vertical wall parts is a target between the vertical wall parts of the curved channel member in a region corresponding to at least the ¼ region on both ends. Forming a curved channel intermediate member that is a larger part than the inner width,
At the end of molding, the vertical part of the curved channel intermediate member is molded so that the bent parts on both sides of the lateral wall part existing in the large part become part of both vertical wall parts of the curved channel member. The method for forming a curved channel member according to claim 1, wherein the twist suppressing portion is formed on an upper portion of the wall portion. A large-diameter bending portion having a configuration corresponding to each portion of the curved channel member, wherein the bending portion is larger than a target curvature radius of the bending portion of the curved channel member in a region corresponding to at least the ¼ region on both ends. Forming a curved channel intermediate member,
At the end of molding, by molding the curved channel intermediate member so that a part of the large-diameter bent portion becomes a part of the vertical wall portion of the curved channel member, the curved channel member is formed on the upper portion of the vertical wall portion. The method for forming a curved channel member according to claim 1, wherein the twist suppressing portion is formed. Preparing a punch having a horizontal wall forming portion for forming a horizontal wall portion of the curved channel member, and a die for forming a vertical wall portion in cooperation with the punch;
The blank is pressed on the lateral wall molding portion of the punch corresponding to the central portion of the curved channel member in the circumferential direction of the punch, and the lateral wall portion is the lateral wall of the punch in the region corresponding to at least the 1/4 region on both ends. A curved channel intermediate member formed into an arch-shaped lateral wall portion formed in an arch shape with a gap between the molded portion,
At the end of molding, the twist suppressing portion is formed on the upper portion of the vertical wall portion by forming the arched lateral wall portion of the curved channel intermediate member into the lateral wall portion and the bent portion of the curved channel member. The method for forming a curved channel member according to claim 1, wherein the forming is performed.   A gap forming means for forming a gap between the horizontal wall forming part of the punch and the horizontal wall part of the curved channel intermediate member is provided in the punch, and the gap forming means is provided between the horizontal wall forming part of the punch and the horizontal wall part. The method for forming a curved channel member according to claim 4, wherein a gap is formed in the curved channel member. A vertical channel part is formed on both sides of the horizontal wall part via a bent part, and a curved channel member in which a curved channel part with a curved cross-sectional center line and a straight channel part with a straight cross-sectional center line are coupled is formed. A method for forming a curved channel member comprising:
At the end of molding, the curved channel member is molded and held in the target shape in the molding die, and at least the straight channel portion of the curved channel member is positioned along the height direction above the vertical wall portion. A method for forming a curved channel member, in which a torsion suppressing portion having a tensile stress and a compressive stress on the outside is formed. It has a configuration corresponding to each part of the curved channel member, and at least in the straight channel part, the inner width between the vertical wall parts is a large part larger than the target inner width between the vertical wall parts of the curved channel member. Molded curved channel intermediate member,
At the end of molding, the vertical part of the curved channel intermediate member is molded so that the bent parts on both sides of the lateral wall part existing in the large part become part of both vertical wall parts of the curved channel member. The method for forming a curved channel member according to claim 6, wherein the twist suppressing portion is formed on an upper portion of the wall portion. A curved channel intermediate member having a configuration corresponding to each part of the curved channel member, wherein at least the straight channel part, the bent part is a large-diameter bent part larger than a target radius of curvature of the bent part of the curved channel member; Molded,
At the end of molding, by molding the curved channel intermediate member so that a part of the large-diameter bent portion becomes a part of the vertical wall portion of the curved channel member, the curved channel member is formed on the upper portion of the vertical wall portion. The method for forming a curved channel member according to claim 6, wherein the twist suppressing portion is formed. Preparing a punch having a horizontal wall forming portion for forming a horizontal wall portion of the curved channel member, and a die for forming a vertical wall portion in cooperation with the punch;
A blank is held on the horizontal wall forming portion of the punch corresponding to the central portion of the curved channel member in the circumferential direction of the punch, and has a configuration corresponding to each portion of the curved channel member. A curved channel intermediate member formed into an arched lateral wall portion formed in an arch shape with a gap between the portion and the lateral wall molding portion of the punch,
At the end of molding, the twist suppressing portion is formed on the upper portion of the vertical wall portion by forming the arched lateral wall portion of the curved channel intermediate member into the lateral wall portion and the bent portion of the curved channel member. The method for forming a curved channel member according to claim 6, wherein the forming is performed.   A gap forming means for forming a gap between the horizontal wall forming part of the punch and the horizontal wall part of the curved channel intermediate member is provided in the punch, and the gap forming means is provided between the horizontal wall forming part of the punch and the horizontal wall part. The method for forming a curved channel member according to claim 9, wherein a gap is formed in the curved channel member. A vertical channel part is formed on both sides of the horizontal wall part via a bent part, and a curved channel member formed of a curved channel part having a curved cross-sectional center line, or a straight channel part having a straight cross-sectional center line in the curved channel part. A method of forming a curved channel member that is formed by forming a coupled curved channel member,
When the curved channel member is molded and held in the target shape in the molding die at the end of molding, the curved channel member is placed inward along the height direction on the outer vertical wall portion on the outer side in the curved radial direction. A method for forming a curved channel member, in which a torsion suppressing portion having tensile stress and compressive stress inside is formed. It has a configuration corresponding to each part of the curved channel member, the inner vertical wall portion and the bent portion on the inner side in the curved radial direction are equal to the target shape of the same portion of the curved channel member, and curved with the inner vertical wall portion Forming a curved channel intermediate member having an inner width between the outer vertical wall portions in the radial direction and a large inner portion larger than a target inner width between both vertical wall portions of the curved channel member. Sometimes, the outer vertical wall portion is formed by forming a bent portion on the outer vertical wall portion side of the large portion of the curved channel intermediate member to be a part of the outer vertical wall portion of the curved channel member. The method for forming a curved channel member according to claim 11, wherein the twist suppressing portion is formed on an upper portion of the curved channel member. It has a configuration corresponding to each part of the curved channel member, the inner vertical wall part and the bent part inside the curved radial direction are equal to the target shape of the same part of the curved channel member, and the inner vertical wall part and the curved diameter The inner width between the outer vertical wall portions on the outer side in the direction is equal to the target inner width between the two vertical wall portions of the curved channel member, and the bent portion on the outer vertical wall portion side is bent by the curved channel member. Forming a curved channel intermediate member having a large-diameter bending portion larger than the target curvature radius of the portion,
At the end of molding, by molding the curved channel intermediate member so that a part of the large-diameter bent portion becomes a part of the vertical wall portion of the curved channel member, the curved channel member is formed on the upper portion of the vertical wall portion. The method for forming a curved channel member according to claim 11, wherein the twist suppressing portion is formed.

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