JP4102731B2 - Bending method of aluminum alloy hollow profile - Google Patents

Description

  The present invention relates to a method for bending an aluminum alloy hollow profile for roof side rails of automobiles.

  In order to reduce the weight of automobiles, the application of aluminum alloy extruded hollow members to the body frame has begun. For example, the roof side rail that extends in the front-rear direction on both sides of the vehicle body is lightened by applying an aluminum alloy extruded hollow shape material, etc., and an inner rib (inner wall portion) is provided on the hollow shape material. It has been proposed to provide shock absorption as a cross-sectional shape.

  The automobile frame has a shape that is largely curved in two or three dimensions in the longitudinal direction for the purpose of avoiding interference with the body design or other body members. Further, in general, many have a projecting (overhanging) flange for joining to the panel member so as to extend in the longitudinal direction.

  A general shape for the roof side rail will be described. As shown in the cross-sectional view of FIG. 7, the roof side rail 10 has a protrusion (extension) flange 7 for joining to the end of the side member outer panel 11 and a protrusion (extension) for joining to the end of the roof panel 13. It has a flange 8 extending along its length.

  The protruding flange 7 for joining to the end of the side member outer panel 11 in the roof side rail 10 shown in FIG. 7 is the roof side rail in the bending direction of the material aluminum alloy hollow shape. This is a protruding flange that protrudes toward the bending inner side (inside bending R). For this reason, wrinkles due to buckling are likely to occur in the flange 7 protruding inward on the roof side rail 10 during bending.

  Fig. 10 shows the bending method of the material aluminum alloy hollow profile. In bending an aluminum alloy hollow profile, a processing device such as a press, multi-stretch, draw bender shown in FIG. 10 is often used. Among them, multi-bender or stretch bender is used for three-dimensional bending with a relatively large bending radius, and press or draw bender is often used for two-dimensional bending with a relatively small radius. Conventionally, in the case of a projecting flange parallel to the bending radius direction, bending is performed while restraining both sides of the projecting flange 7 on the inner side of the material aluminum alloy hollow profile 1a with a mold.

  However, when the angle of the projecting flange has an angle with respect to the bending radial direction, both sides of the projecting flange cannot be completely restrained, and as shown in FIG. A wrinkle A is generated on the protruding flange 7 of the side rail 10. This wrinkle is much more likely to occur in the protruding flange whose end can be freely deformed than in the closed section.

  When the wrinkle A is generated on the protruding flange 7 on the inner side of the roof side rail 10, correction of the wrinkle A is inevitable after the bending process. Also, if the wrinkle A is large, it cannot be corrected and the water-tight joint with the end of the side member outer panel 11 shown in FIG. 7, the joint strength cannot be ensured, or the joint itself is impossible. Become. As a result, the aluminum alloy hollow profile cannot be applied to the roof side rail. This is a problem that occurs in common with other vehicle body frames having a protruding flange on the bent inner side, such as a protruding flange on the bent inner side of the front side member.

On the other hand, various bending methods for preventing wrinkling of the flange of an aluminum alloy hollow shape member having a flange protruding inwardly from bending have been proposed. For example, in the projecting flange of the front side member, except for the joint portion of the projecting flange with the panel member, the other projecting flange portion is provided with an easily deformable portion to generate wrinkles, and the joint portion of the projecting flange is flattened. There is a bending method to ensure the degree (see Patent Document 1). In addition, a heating element is embedded in a bending die in draw bending, etc., and the bent portion of the hollow shape member including the protruding flange is heated to 180 to 250 ° C. to perform bending and prevent bending of the flange. There exists a processing method (refer patent document 2).
Japanese Unexamined Patent Publication No. 7-328735 (Pages 1 and 2, Fig. 1) JP-A-8-99128 (pages 1 and 2, Fig. 1)

  However, the method of generating wrinkles by providing an easily deformable portion in another protruding flange portion as in Patent Document 1 is applied only when the portion where the flatness of the joint portion in the protruding flange is to be ensured is very small. it can. In other words, it cannot be applied when the protruding flange portion to ensure the flatness is long or over the entire longitudinal direction of the flange, and even when viewed as a whole member, the generation of wrinkles can be fundamentally suppressed. It can be said that there is no passive solution.

  This point is the same in Patent Document 2 described above. When an aluminum alloy hollow shape is heated to 180 to 250 ° C. and formed warm, depending on the aluminum alloy component, the hollow shape may be reduced by age hardening or annealing. The mechanical properties of the profile may change, failing to meet the characteristics required for a body frame, and may require heat treatment for further recovery. Also, including this heat treatment, embedding the heating element in the bending mold itself increases the cost of bending. And, except for the flange parallel to the bending radius direction, the restriction by the mold is impossible and it cannot be applied.

  On the other hand, as a more general countermeasure, there is a method of using a stretch bender and bending while applying tension in the longitudinal direction of the shape member. However, in the case of an aluminum material, there is a problem that elongation is small compared to a steel plate and it is easy to break, and there is a case where a tension enough to suppress wrinkles cannot be applied.

  For this reason, it is difficult to bend with an aluminum alloy hollow shape member such as a roof side rail having a shape that is curved two-dimensionally or three-dimensionally in the longitudinal direction and having a flange protruding inside the bending. If this is not possible, it is necessary to allow the generation of wrinkles, or it is necessary to change the design to a shape that does not generate wrinkles. And these problems become a big factor which hinders the expansion | deployment expansion of the aluminum alloy hollow shape material to a motor vehicle frame.

  In view of this point, the present invention is an aluminum alloy hollow shape member having a flange projecting inwardly, such as for an automobile roof side rail, and has a shape that is curved two-dimensionally or three-dimensionally in its longitudinal direction. It is an object of the present invention to provide a bending method of an aluminum alloy hollow profile that can be bent.

For this purpose, the gist of the bending method of the aluminum alloy hollow profile of the present invention is a bending method of an aluminum alloy hollow profile having a flange projecting inward in the longitudinal direction, which is bent. that two of said hollow shape member, after which with the match the protruding flange between each other diagonally to prepare a profile which is integrated into the connecting features, and bending the profile in which the integrated allowed, this In the abutting portion between the projecting flanges of the shape member, each is divided into two hollow shape members.

  As described above, in the method of bending an aluminum alloy hollow shape member having a flange protruding inside the bending, a technique for bending each individual aluminum alloy hollow shape member is known. However, as in the present invention, the aluminum alloy hollow shape members having flanges projecting inwardly from bending are formed by bending the integrated shape members in such a manner that the projecting flanges are abutted with each other, and then the shape materials are two-folded. There has been no idea in the past that it is divided into two hollow sections and used for roof side rails.

  The shape in which the two projecting flanges are obliquely butted together and the shape of the two hollow shapes is integrated. The bending process is achieved by integrating the projecting flanges that are inside the bend. This is based on the technical idea of improving the buckling limit stress of the projecting flange at the time of preventing the occurrence of wrinkles on the projecting flange on the inner side of the bend.

The buckling limit stress σ _c of the protruding flange can be expressed by σ _c × r ∝k (t / b) ² . Where r: bending radius, k: buckling coefficient, t: protruding flange thickness, b: protruding flange plate width.

In order to increase the buckling limit stress σ _c of the projecting flange, the bending radius r 1, buckling coefficient k 2, projecting flange wall thickness t, etc. are increased, or the projecting flange plate width b 1 is decreased. However, the protruding flange thickness t, the protruding flange plate width b, and the like are determined by the design of the frame such as the roof side rail and the front side member of the vehicle body.

  In order to reduce the compressive stress applied to the shape member, there is a method of (1) applying tension or (2) increasing the bending radius r. However, in the method (1), the risk of breakage increases as shown by 0014. On the other hand, in the method (2), the bending radius r is determined by the design of the frame as in the case of the thickness t and the width b. Therefore, constraining the bending radius r, the protruding flange thickness t, the protruding flange plate width b, etc. from the viewpoint of preventing wrinkle generation of the protruding flange leads to limiting the degree of freedom of this design. This hinders the expansion of adoption of aluminum alloy hollow shape materials, and is not preferable.

For this reason, the present inventor has focused on increasing the buckling coefficient k in the formula of the buckling limit stress σ _c . Then, it was found that if the projecting flanges are brought into contact with each other and the two hollow members are integrated, the projecting flange on the inner side of the bend can be closed, and the buckling coefficient k of the projecting flange can be increased. Incidentally, according to the analysis of the present inventor, when the angle between the projecting flanges joined by the projecting flanges is an angle of 135 or less, the buckling coefficient k of the projecting flange is determined by the elastic buckling. Under conditions, the buckling factor k can be increased by about 5 times for a single (individual) protruding flange.

By increasing the buckling coefficient k of the protruding flange, it is possible to increase the buckling limit stress σ _c of the protruding flange that is the inside of the bending at the time of bending. This is a value sufficient to allow normal bending of the material aluminum alloy hollow profile without generating wrinkles in the protruding flange on the inner side of the bend. A method for increasing the buckling coefficient k of the projecting flanges by integrating the projecting flanges is usually designed or used in a frame such as a roof side rail or a front side member of a vehicle body. It is effective in the range of the protruding flange wall thickness t and the protruding flange plate width b, and can be widely applied.

  However, the effect of increasing the buckling coefficient k of the projecting flanges by integrating the projecting flanges is that the angle between the projecting flanges that face each other (inner angle) and the inner side of the bending by the bending mold It is greatly influenced by the restraint state. In other words, the angle formed by the projecting flanges that face each other is preferably 135 or less. In this case, the protruding flanges are butted against each other at an angle.

  If the design shape of the body frame is a two-dimensional curved shape (unless further bending is required), the integrated flange is joined after the bending. It is cut at a portion (butting portion) and divided into two hollow shapes, and each is used as a frame such as a roof side rail or a front side member of a vehicle body. Especially in the case of bending with a press, stretch bender or draw bender, two parts are produced at the same time, and a bending die is used to cut immediately after bending, thereby shortening the processing time. Is also possible.

  Further, when further bending work is required after this bending work, such as the design shape of the body frame is a three-dimensional curved shape, the following bending work is performed. In other words, bending in the direction in which wrinkles may occur in the protruding flange that is inside the bend is performed without dividing each of the two hollow shapes into an integrated hollow shape, and then in the other direction. It becomes possible to obtain a wrinkle-free product by bending.

  Even if the hollow shape has a two-dimensional bent shape, if the joint angle of the projecting flange is not sufficient, the product shape (bending radius r, wall thickness t) can be obtained by performing bending twice described later. It is possible to obtain a product without wrinkles without changing the flange width b).

  Embodiments of the present invention will be specifically described below with reference to the drawings. First, an aluminum alloy profile integrated so as to have a shape in which the projecting flanges of these two hollow profiles are obliquely butted and joined together, and preparation (production method) of the profile will be described below. .

  FIGS. 1 and 2 are cross-sectional views of a profile showing an example of an integrated material aluminum alloy profile according to the present invention. In these embodiments of FIGS. 1 and 2, the projecting flanges 7a and 7b, which are the inner sides of each of the hollow shape members 1a and 1b having cross-sectional shapes that are symmetrical with respect to each other, are abutted obliquely to each other, and a butted portion 13a 13b shows an embodiment in which they are joined and integrated. These hollow shapes 1a and 1b are hollow shapes that are to be bent, and that are to be bent individually. The hollow members 1a and 1b have the same cross-sectional shape over the long longitudinal direction, such as an extruded hollow member described later.

  Here, the cross-sectional shapes of the individual hollow members 1a and 1b are the vertical walls 2 (2a, 2b), 3 (3a, 3b) and the lateral ribs 4 (4a, 4b), 5 (5a, 5b) and And two hollow portions (hollow spaces) 9 and 9 whose central portions are partitioned by the middle ribs 6 (6a and 6b). The overall shape of the cross-section of the hollow profile 1a (same for 1b) consists of two vertical walls 2a and 3a projecting outward from each other, two parallel horizontal ribs (upper and lower horizontal walls) 4a and 5a connecting them, hollow It has a substantially hexagonal shape composed of the portion 9. Here, the vertical walls 2a and 3a are reinforced by the middle rib 6a.

  Then, from the vertical walls 3a and 3b of the hollow shape members 1a and 1b, the protruding flange 7a protrudes toward the lower right in the figure, and the protruding flange 7b protrudes symmetrically outward toward the lower left in the figure. Yes. Further, from the vertical walls 2a and 2b of the hollow shape members 1a and 1b, the protruding flange 8a protrudes toward the upper left in the drawing, and the protruding flange 8b protrudes symmetrically outward toward the upper right in the drawing.

  In the embodiment of FIG. 1, the aluminum alloy hollow shapes 1a and 1b are formed such that the projecting flanges 7a and 7b are abutted diagonally and at the tip of each other, and are directly joined to each other at the butted portion (tip) 13a. , Showing an integrated embodiment.

  On the other hand, in the embodiment of the aluminum alloy hollow shape members 1a and 1b in FIG. 2 (a), it is the same as the embodiment in FIG. 1 until the protruding flanges 7a and 7b are abutted diagonally. . However, the flanges 7a and 7b are joined to each other via a flat linear abutting portion 13b having a certain width and are integrated. In the case of the embodiment of FIG. 2 (a), the butting angle θ between the projecting flanges 7a and 7b is smaller than that of the embodiment of FIG. 1 due to the final frame shape design such as the roof side rail.

  In such a case, as in the embodiment of FIG. 1, when the flanges 7a and 7b are directly butted according to the present invention, the main bodies of the hollow shape members 1a and 1b overlap each other, and directly I ca n’t match. Therefore, in such a case, in order to open the gap between the main bodies of the hollow shape members 1a and 1b and prevent the overlap, the flange 7a is interposed via a flat linear butting portion 13b having a certain width. And 7b. In this case, the butting angle θ between the projecting flanges 7a and 7b is an angle formed by an extension line (dotted line) between the flanges 7a and 7b. By integrating the projecting flanges 7a and 7b in this way, it is possible to improve the buckling limit stress of the projecting flange at the time of bending, and to prevent wrinkles from occurring on the projecting flange that is inside the bend.

  By joining the tips of the protruding flanges, which are essentially free ends, to each other, the integrated protruding flanges 7a and 7b are deformed as individual plates, so the state of the flat plate-like individual protruding flanges 7a and 7b The buckling coefficient k of the protruding flange can be remarkably increased to about 5 times or more compared with the case of bending at.

  At this time, when the butting angle θ between the projecting flanges 7a and 7b that are obliquely butted and integrated with each other (the inner angle between the projecting flanges 7a and 7b that are butted together) is 135 degrees or less, It is possible to enhance the effect that the integrated projecting flanges 7a and 7b are deformed as individual plates. For this reason, in order to increase the buckling coefficient k of the protruding flange, the angle θ is preferably set to 135 degrees or less.

  On the other hand, when the butting angle between the projecting flanges 7a and 7b is larger than 135 degrees, the projecting flanges 7a and 7b are easily deformed as a single flange. For example, when the butting angle θ is 180 degrees, the protruding flanges 7a and 7b are parallel or flush with each other, so that the protruding flanges 7a and 7b form a single wide flange surface (flange width 2b). Will do.

Here, since the buckling limit stress of a member or a part depends on the aforementioned k × (t / b) ² , the flange width is doubled even if the buckling coefficient k is about 5 times or more. The effect is almost offset. Therefore, the abutting angle θ between the integrated projecting flanges 7a and 7b needs to be considered so that the main bodies of the hollow shape members 1a and 1b do not contact each other, but is preferably an angle of 135 degrees or less. .

  The projecting flanges 7a and 7b and the individual hollow profiles 1a and 1b are integrated with each other by forming the individual hollow profiles 1a and 1b separately by extrusion or the like, and then inside each bend. The protruding flanges 7a and 7b may be joined together in the longitudinal direction by fusion welding of FSW, spot, TIG, MIG or the like at the butting portion 13a. However, this method has a disadvantage in that the joining step by welding is increased. For this reason, it is preferable to obtain an overall shape in FIGS. 1 and 2 in which hollow shapes 1a and 1b having cross-sectional shapes that are symmetrical to each other are integrated in advance by extrusion.

  The integrated extruded profile itself is appropriately manufactured by a conventional method including ingot casting, homogenization heat treatment, hot extrusion, tempering heat treatment, and the like as main processes. By using such extruded profiles, even if the cross section of the integrated material aluminum alloy profile of the present invention has a complicated shape as shown in FIGS. It is possible to manufacture easily and efficiently.

  The protruding flanges 8a and 8b, which are the outer sides of the bending process, are not subjected to buckling deformation because the tensile stress acts during the bending process, and it is not necessary to take the measures of the present invention.

  In the embodiment of FIGS. 1 and 2, hollow sections 1a and 1b having cross-sectional shapes that are symmetrical with respect to each other become the respective roof side rails that exist on the left and right sides of the vehicle body after bending. The projecting flanges 7a and 7b are inside the bend at the time of bending, and as shown in FIG. 7, the projecting flange for joining to the end of the side member outer panel 11 after the bending, as shown in the usage mode of the roof side rail. It becomes. In addition, the protruding flanges 8a and 8b are bent outside at the time of bending, and become protruding flanges for joining to the end of the roof panel 13 after bending. In FIG. 7, reference numeral 12 denotes an adhesive or a mechanical joining means for the joining.

  The cross-sectional shapes of these individual aluminum alloy hollow members are not limited to those shown in FIGS. 1 and 2, but are determined by the design of the frame such as the roof side rail and the front side member of the vehicle body. For example, as the overall cross-sectional shape of the material aluminum alloy hollow shape, a hollow structure such as a mouth shape or a polygon is appropriately selected in addition to the substantially hexagonal shape shown in FIGS. In addition, a reinforcing middle rib can be appropriately inserted into the hollow structure so that the cross-sectional shape thereof becomes a day shape (the embodiment shown in FIGS. 1 and 2), an eye shape, a square shape, and the like.

  The cross-sectional shapes of the individual aluminum alloy hollow members to be integrated do not necessarily have to be bilaterally symmetrical or have the same cross-sectional shape as shown in FIGS. The cross-sectional shape and size of the hollow members to be integrated can be appropriately changed according to the body frame to be obtained, the production efficiency of the bending process, and the like. Further, one of the aluminum alloy hollow shapes to be integrated may be a dummy material that is not a product target.

  A description will be given below of the manner of bending by draw bending or the like of the shapes in which the hollow shapes are integrated. Fig. 3 (a) is a perspective view showing an aspect of bending the integrated shape of Fig. 1, Fig. 3 (b) is a side view of Fig. 3 (a), and Fig. 3 (c) is integrated. It is a perspective view which shows the aspect which is making the shape member made to be bent.

  In FIG. 3 (a) to FIG. 3 (c), the hollow shape members 1a and 1b are integrally extruded and integrated in advance. Bending is performed by pressing against the curved mold 20 corresponding to the above bending degree (bending degree). As shown in FIG. 3 (a), during bending, each part that is inside the bent portion of the integrated profile, that is, the integrated flanges 7a and 7b, and the hollow shape in the vicinity of this flange The vertical wall 3a and the lower horizontal wall 5a of the hollow profile 1a, which are the material parts, and the vertical wall 3b and the lower horizontal wall 5b of the hollow profile 1b are constrained by the mold 20 from the inside of the bending.

  A drawing bender clamping die (clamping die) 20 is divided into left and right dies 20a and 20b. The left and right molds 20a, 20b are formed in the outer shape of the restraint portion 22 (restraint slope or restraint curved surface) corresponding to the outer shape of the flanges 7a, 7b, the vertical wall 3a of the hollow profile 1a, and the lower lateral wall 5a. Each has a corresponding restraint portion 21 (a restraint slope or a restraint curved surface). C is a gap between the left and right molds 20a and 20b where the shear cutting blade enters (lowers) in order to separate (divide) the hollow members 1a and 1b described later. In this embodiment, the gap C is provided by dividing the mold 20, but it is not always necessary to divide the mold 20, as long as a space for the shear cutting blade can be secured, and the gap C is formed in the mold 20. It is good also as chopped groove shape.

  In FIG. 3 (c), reference numeral 23 denotes a bending die. 3A to FIG. 3C, the pressure die that restrains the hollow member together with the bending die 23 and from the opposite side of the bending die 23 is not shown.

  At this time, in order to suppress wrinkling of the projecting flanges 7a and 7b, the surface (lower surface) of the projecting flanges 7a and 7b, which is the inside of the bend in the integrated shape member, and the mold corresponding to this are bent. Preferably, 20 surfaces 22 are in contact. That is, in the embodiment of FIGS. 3 (a) to 3 (c), in order to suppress wrinkling of the projecting flanges 7a and 7b, the surface (lower surface) of the projecting flanges 7a and 7b is contacted during bending. A surface 22 is provided on the mold 20.

  In the present invention, the present invention can be carried out only by changing the material aluminum alloy shape, except that a die having a shape corresponding to the shape of the protruding flanges 7a and 7b is necessary. That is, there is an advantage that a normal bending method can be adopted and conditions and bending part design conditions can be applied. Other than the above drawing benders, stretch benders, multi-benders, etc. can be applied as appropriate, and integrated shapes can be bent by cooperating with pressure dies, gripping (clamping) dies, and feeding (feeding) dies. . In such bending, a neutral shaft as shown in FIG. 3 (c) is provided.

  If the design shape of the vehicle body frame is a two-dimensional curved shape after this bending process (if no further bending process is required), the profile is cut (divided) after the bending process shown in FIG. At this time, as shown in the sectional view of FIG. 4, the profile is cut at the flange abutting portion 13a (joint portion) of the integrated flanges 7a and 7b, and divided into two hollow profiles 1a and 1b, respectively. Is done. And it is used as frames, such as the roof side rail of a vehicle body, and a front side member. This cutting is performed from the vertical direction by an appropriate cutting means such as a cutter or a shear, for example, a shear cutting blade 24.

  When dividing into these two hollow shapes, in the embodiment shown in FIG. 1, the abutting portion 13a between the projecting flanges 7a and 7b is cut and divided by an appropriate cutting means. Further, in the embodiment of FIG. 2, in order to remove the linear abutting portion 13b (unnecessary) interposed between the projecting flanges 7a and 7b, at each of the two ends of the projecting flanges 7a and 7b, for example, As shown by a dotted line 14, the cut is made obliquely by an appropriate cutting means, and separated and divided.

  As described above, according to the present invention, an additional process of dividing the integrated shape after bending is required. However, in the bending process that occupies a large part in the frame manufacturing process, two aluminum alloy hollow shapes can be bent at the same time, and the efficiency can be improved. For this reason, there is also an advantage that the overall frame manufacturing process can be made more efficient.

  When the body frame has a design shape such as a three-dimensional curved shape and requires further bending, further bending is performed in a predetermined direction after the cutting and dividing. Regarding the bending process of the second step, the so-called bending direction of the first step described in FIG. 3, and the bending process sequence, considering the possibility of wrinkling of the protruding flange on the inner side of the bending, It is selected appropriately.

  FIG. 5 (a) is a perspective view showing one shape 1a after bending and dividing in the first step, which is further subjected to bending in the second step. FIG. 5 (b) is a sectional view showing the second bending process of the shape member 1a. In FIG. 5 (a), the solid line rising upward in the figure is the bending direction of the second process, and the dotted line rising upward in the figure is the bending direction of the profile in the second process.

  The bending process of the second step of the profile 1a shown in FIG. 5 (b) is performed so that no compressive stress is applied to the protruding flange 7a of the profile 1a with respect to the bending direction of the second process of FIG. 5 (a). The mode which is bending-processed is shown. That is, in the bending direction of the second step in FIG. 5 (a), compressive stress is applied to the protruding flange 7a of the profile 1a, so that the bending process is performed by bringing the end surface 25a of the mold 25 into contact with the protruding flange 7a. is doing. If the bending direction in the second process is such that no compressive stress is applied to the protruding flange 7a of the profile 1a, wrinkles will not occur even if the protruding flange 7a is bent freely without contact with the mold. It is suppressed.

  As an aluminum alloy that satisfies the required characteristics according to the body frame of these hollow shape members, 5000 series, which is generally used for this kind of structural member application, is defined by AA to JIS standards, or is included in these standards. 6000 series, 7000 series and other general-purpose alloys with relatively high yield strength, selected from tempered aluminum alloys such as O 2, T4, T5, T6, and T7.

The shape of the present invention shown in FIG. 1 (the shape obtained by integrating the hollow shapes 1a and 1b) and the normal (conventional) single hollow shape 1a shown in FIG. The state of wrinkle generation was compared by FEM analysis. FIG. 9 (a) shows the length and thickness of each part of the hollow profile 1a, which is a premise of the analysis. FIG. 9 (a) shows only the thickness of each part of the hollow profile 1a, and the thickness of each part on the hollow profile 1b side of the profile of the present invention is the same as the corresponding part of the hollow profile 1a. is there. Further, here, the wrinkle generation state was evaluated by the amount of surplus at the tip of the protruding flange 7. As shown in FIG. 9 (b), the amount of this surplus is a parameter expressed by the following equation by comparing the design line length L ₀ at the tip of the protruding flange 7 with the actual length L after bending. It was.
Meat surplus (%) = [(L ₀ −L) / L] × 100

  At this time, in order to calculate the surplus amount when variously changing the bending inner radius Ri, a multi-bender capable of changing the bending radius without changing the mold was assumed for the bending process. The analysis was performed using the general-purpose dynamic explicit method software LS-DYNA3d. In this calculation, we assumed a bending process between the movable mold and the fixed mold, and investigated the deformation mode when the profile was evenly bent. Two types of tempered materials, T1 and T5 of 6062 aluminum alloy, were assumed as test materials.

  FIG. 8 shows the relationship between the amount of excess margin at the tip of the protruding flange 7 and the bending radius. In FIG. 8, the vertical axis represents the above-mentioned surplus amount (%) indicating the degree of occurrence of wrinkles, and the horizontal axis represents the bending radius Ri (mm). In the four curves in Fig. 8, the thin line represents the conventional method, the thick line represents the method of the present invention, the white circle mark and the black circle mark represent the 6062 aluminum alloy T1 material of the conventional method and the present invention method, the white square mark and the black square mark. 6062 aluminum alloy T5 material of the conventional method and the present invention method. In FIG. 8, when the amount of excess on the vertical axis is 0%, it indicates that wrinkles are not generated on the protruding flange 7 even by bending.

  As shown in Fig. 8, the method of the present invention can be applied to the higher strength 6062-T5 material (black square bold line), the bending radius is reduced to 550 mm, and 6062-T1 material (black circle thick line). Even when the bending radius is reduced to 450 mm, the surplus amount is 0%, and almost no wrinkles are generated in the projecting flange 7 of the bent hollow member.

  On the other hand, in the ordinary bending of a single hollow profile, even if the bending radius is as large as 750 mm, either 6062-T5 (white square-marked thin wire), 6062-T1 (white circle-marked thin wire), or The amount of excess meat is 1 to 3% and wrinkles are generated. And the tendency of this wrinkle generation becomes so remarkable that a bending radius becomes small. Therefore, the effect of improving the buckling limit stress of the protruding flange 7 which is the inside of the bending according to the present invention is supported.

  According to the present invention, wrinkles A are not generated on the protruding flanges on the bending inner side of the vehicle body frame such as the roof side rail, so that the wrinkle correction work after bending is not necessary. Further, it is possible to ensure watertight joining with the end of the side member outer panel 11 shown in FIG. These effects are the same in other body frames such as a front side member having a protruding flange on the inner side of the bend.

  As described above, according to the present invention, even for an aluminum alloy hollow shape member having a flange protruding inside the bend, such as for an automobile roof side rail, it is curved two-dimensionally or three-dimensionally in its longitudinal direction. It is possible to provide a method for bending an aluminum alloy hollow profile that can be bent into a shape. Therefore, the application of the aluminum alloy to an automobile frame or the like can be expanded.

It is sectional drawing which shows an example of the raw material aluminum alloy shape material integrated of this invention. It is sectional drawing which shows an example of the raw material aluminum alloy shape material integrated of this invention. FIG. 3 (a) is a perspective view and FIG. 3 (b) is a cross-sectional view showing an embodiment of bending by draw bending according to the present invention. It is sectional drawing which shows the aspect of the cutting | disconnection of the profile after a bending process. It is sectional drawing which shows the bending process of a 2nd profile. It is a perspective view which shows an example of the aluminum alloy hollow shape material bent by this invention. It is sectional drawing which shows the aspect which applied the aluminum alloy hollow shape material to the automobile roof side rail. It is explanatory drawing which shows the relationship between the amount of surplus at the front-end | tip of the protrusion flange 7 in an Example, and a bending radius. It is explanatory drawing which shows the analysis conditions in an Example. It is a perspective view which shows the example of the conventional bending method. It is a perspective view which shows the conventional aluminum alloy hollow shape material by which the bending process was carried out.

Explanation of symbols

1: Aluminum alloy hollow shape, 2, 3: Vertical wall, 4, 5: Horizontal rib, 6: Medium rib,
7: Protruding flange, 8: Protruding flange, 9: Hollow space, 10: Roof side rail,
11: Side member outer, 12: Joining means, 13: Roof panel,
20, 23, 25: Mold, 21, 22: Restraint part, 24: Shear cutting blade,

Claims (4)

A bending method of an aluminum alloy hollow shape member having a flange protruding inward in the longitudinal direction, the two hollow shapes to be bent, and the protruding flanges of each other are abutted diagonally After preparing the shape integrated into the joined shape and bending the integrated shape, the two hollow shapes are respectively formed at the abutting portions of the protruding flanges of the shape. A method of bending an aluminum alloy hollow profile characterized by dividing.   The method of bending an aluminum alloy hollow profile according to claim 1, wherein an angle formed by the butted projecting flanges is 135 degrees or less.   The method of bending an aluminum alloy hollow profile according to claim 1 or 2, wherein the hollow profile is further bent after the bending to obtain an aluminum alloy hollow profile bent in a three-dimensional direction.   The method for bending an aluminum alloy hollow shape member according to any one of claims 1 to 3, wherein the aluminum alloy hollow shape member is used for a roof side rail of an automobile.

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