JP4133302B2 - Energy absorption member for car body - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an energy absorbing member for a vehicle body that has excellent load energy absorption performance at the time of a vehicle body collision and has excellent mounting properties.
[0002]
[Prior art]
In order to ensure the safety of passengers, an energy absorption box or crash box that absorbs load energy by crushing and deforming in the axial direction when a heavy load is applied in the axial direction at the time of a vehicle collision A so-called energy absorbing member is provided.
[0003]
Typical examples of the vehicle body energy absorbing member include a bumper stay provided on the rear surface of a bumper reinforcing material such as a front and rear, an energy absorbing member provided between the bumper stay and the vehicle body side member member, and the like.
[0004]
The structure of these energy absorbing members basically consists of a hollow material having a circular or rectangular cross-sectional shape extending in the longitudinal direction (axial direction).
[0005]
The energy absorbing member is disposed such that the bumper stay, the energy absorbing member, and the like extend in a substantially horizontal direction in the vehicle body length direction. These energy absorbing members are not damaged or scattered when a heavy load is applied to the hollow material in the axial direction in the event of a collision at the front or rear of the vehicle, depending on each use (attachment) part of the vehicle. In addition, a function of crushing and deforming in a bellows shape in the axial direction to absorb load energy is required.
[0006]
In recent years, high-strength extruded aluminum materials such as 5000 series, 6000 series, and 7000 series have begun to be used for these energy absorbing members to reduce the weight of the vehicle body, instead of steel materials that have been used in the past. Yes.
[0007]
In order to further enhance the energy absorbing performance of these energy absorbing members, a tapered automobile energy absorbing member (impact absorbing member) 40 as shown in a perspective view in FIG. 11 has been conventionally proposed (see Patent Document 1). .
[0008]
[Patent Document 1]
JP 2000-53017 (1-3 pages, Fig. 1-3)
[0009]
As shown in FIG. 11, the tapered automobile energy absorbing member 40 of Patent Document 1 has a tapered shape in which the outer peripheral wall 41 becomes thinner toward the front side of the vehicle body (thicker toward the rear side of the vehicle body). And, it has a HAT-type hollow shape integrally including a front wall 42 on the front side of the vehicle body and a flange 43 on the rear side, and the flange 43 has a front plate 42 with bolt holes 44a to 44c via a mounting plate 44. It is fixed at the front end.
[0010]
In addition to Patent Document 1, the steel plates formed in a U-shape are butted together and welded together to form a hollow material integrally. An energy absorbing member having a tapered shape that becomes narrower is actually used.
[0011]
Such a taper-shaped energy absorbing member has a structure where the root becomes thick with respect to the collision load from the front surface, and in terms of the secondary moment of section, the entire outer wall 41 has the same outer diameter as compared to the case where the outer peripheral wall 41 has the same outer diameter. Buckling is less likely to occur. For this reason, when a large load is applied to the hollow material in the axial direction, the hollow material can be deformed in a bellows shape in the axial direction without being damaged or scattered, thereby improving the performance of absorbing load energy. it can. Moreover, even if the collision load is input at an angle slightly inclined with respect to the length direction, there is an advantage that load energy absorption performance can be easily secured.
[0012]
[Problems to be solved by the invention]
However, when the energy absorbing member 40 as described in Patent Document 1 is to be manufactured using an aluminum alloy, the manufacturing itself is difficult. That is, the energy absorbing member 40 as in Patent Document 1 has a closed cross section having a front wall 42 on the front side of the vehicle body, and further has a HAT-type hollow shape integrally having a flange 43 extending outward on the rear side. Therefore, whether the aluminum alloy hollow shape material is used as the starting material or the aluminum alloy plate material is used as the starting material, the tapered body is manufactured by pressing or machining, and the flange 43 is manufactured integrally. It is very difficult to do. In addition, there is a problem that the processing process becomes very complicated or complicated and is not economical.
[0013]
And among the aluminum alloys, such as the 7000 series aluminum alloy having high strength and small elongation, the press working or machining is relatively difficult, and when the tapered body portion and the flange 43 are provided integrally, It tends to cause rough skin such as cracks and micro cracks. Furthermore, depending on the conditions of pressing or machining, the remaining elongation may remain in the deformed portion.
[0014]
If these cracks, rough skin, or residual elongation exists in the deformed portion and its periphery, the crushing strength of the deformed portion and its peripheral portion is significantly reduced. For this reason, the deformed portion is not easily collapsed when a large load is applied as in the case of a vehicle collision, but is easily collapsed when a smaller load is applied (a starting point of collapse), and the energy absorption performance is significantly reduced. On the other hand, pressing or machining so as to eliminate these cracks, rough skin, or residual elongation leads to the complexity and complexity of the processing steps described above.
[0015]
For this reason, it is difficult to integrally manufacture the energy absorbing member as in Patent Document 1 including its flange, and the tapered body portion and the flange 43 are separately manufactured, welded, etc. It must be joined with. However, when integrated by welding, the number of parts and joints increase, so that a reduction in joint strength and a reduction in collision energy absorption performance associated therewith become a problem. For this reason, it is necessary to devise a joining method for preventing the joint strength from being lowered, and there is a practical problem that it becomes more complicated regardless of welding or mechanical joining.
[0016]
As a result, it is difficult to produce a tapered energy absorbing member with an aluminum alloy material, and the actual embodiment has to be the above-described integrated hollow material by welding using a steel plate forming material.
[0017]
Accordingly, an object of the present invention is to provide an aluminum alloy energy absorbing member for a vehicle body that is integrally provided with a tapered shape of a body portion, and further a flange for joining, etc., without degrading energy absorbing performance. Is.
[0018]
[Means for Solving the Problems]
  In order to achieve this object, the gist of the energy absorbing member for a vehicle body of the present invention is made of an aluminum alloy extruded hollow material, and is bonded to the vehicle body member so that the axial direction of the hollow material is the load application direction, An energy absorbing member that absorbs load energy by crushing and deforming in the axial direction of the hollow material when added, and has a tapered shape in which the outer diameter of the hollow material increases toward the rear side in the axial direction with respect to the load. Is formed by expanding the diameter of the hollow material by electromagnetic forming, and at the end in the axial direction of the hollow material, there is a flange that has a joint surface shape that matches the joint surface shape of the vehicle body member and spreads outward This flange is formed by expanding the end of the hollow material axial direction by electromagnetic forming.Pressed against the molding surface,This flange is formed integrally with the hollow material.The surface opposite to the surface pressed against the mold is a bonding surface,It is joining with the said vehicle body member.
[0019]
As described above, the aluminum alloy energy absorbing member having a tapered body shape as in the present invention has a structure in which the root becomes thick with respect to the collision load from the front surface. Compared to when the diameters are the same, the overall buckling is less likely to occur. For this reason, when a large load is applied to the hollow material in the axial direction, the hollow material can be deformed in a bellows shape in the axial direction without being damaged or scattered, thereby improving the performance of absorbing load energy. it can. Moreover, even if the collision load is input at an angle slightly inclined with respect to the length direction, there is an advantage that load energy absorption performance can be easily secured.
[0020]
  Further, in the present invention, a tapered body shapeAnd contactThe combined flange is formed integrally with the hollow member by expanding the diameter of the aluminum alloy hollow member itself by electromagnetic forming. As described later, electromagnetic forming forms a material (hollow material) by ultra-high-speed deformation of the forming material by electromagnetic force. For this reason, unlike press working or machining with a slow deformation speed, the above-described cracking, rough skin, or residual elongation is less likely to occur when forming a tapered body shape or forming a joining flange. Moreover, since the formation of the tapered body portion and the flange for joining can be formed integrally, the above-described problem of securing the joint strength at the joint portion in the divided structure can be solved.
[0021]
  Also, since electromagnetic forming is an ultra-high-speed deformation caused by strong electromagnetic force, the tapered body shapeAnd contactEven if these flanges have complicated shapes, they can basically be formed by a single molding process. For this reason, there is no problem that the machining process becomes complicated, such as pressing or machining, or the number of parts increases and becomes complicated.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the energy absorbing member of the present invention will be specifically described. 1 to 7 are perspective views showing embodiments of the energy absorbing member of the present invention.
[0023]
First, in FIGS. 1 to 4, FIGS. 1 (a), 2 (a), and 3 (a) show an aluminum alloy hollow material 7a that is a circular tube (a cross section is circular) as a material, and FIG. a) shows an aluminum alloy hollow material 7b having a rectangular cross-section tubular shape (a cross section having a mouth-shaped tubular shape) as a material.
[0024]
  FIG. 1 (b), FIG. 2 (b), and FIG. 3 (b) show tapered energy-absorbing members 1a, 1c, and 1e of the present invention in which the diameter of the tubular aluminum alloy hollow material 7a is expanded by electromagnetic forming.(However, the end flange is not formed). The energy absorbing member 1a has a circular outer shape, 1c has a hexagonal polygonal shape, and 1e has a rectangular outer shape.
[0025]
  FIG. 4 (b) shows the tapered energy-absorbing member 1g of the present invention, in which the aluminum alloy hollow material 7b having a rectangular cross section is expanded by electromagnetic forming.(However, the end flange is not formed). The same outer shape of the energy absorbing member 1g as that of the energy absorbing member 1a in FIG. Thus, the advantage of electromagnetic forming is that a hollow material having a different cross-sectional shape, such as a circular tube, can be easily formed from a hollow material having a rectangular cross-section tubular material.
[0026]
Each of these energy absorbing members has a structure in which the base becomes thicker with respect to the collision load from the front surface, and the outer diameter of the hollow material in the axial direction with respect to the collision load direction indicated by F1, respectively, Each has a tapered shape (tapered body) that gradually increases in thickness toward the rear side, in other words, gradually decreases toward the front side with respect to the load direction.
[0027]
In the case of a bumper stay or an energy absorbing member, as will be described later, it is supported in the axial direction by the vehicle body member at both axial end portions 3a, 3b of the hollow member 3 or the flanges 2a, 2b. In the case of such a use mode, the tapered energy absorbing member is entirely in comparison with the hollow material having the same outer diameter in terms of the secondary moment from the point of view of the secondary moment with respect to the collision load from the front surface. Buckling is less likely to occur and load energy absorption performance can be increased. Moreover, even if the collision load is input at an angle slightly inclined with respect to the length direction, it is easy to ensure load energy absorption performance.
[0028]
Moreover, in the present invention, these tapered body shapes are formed by expanding the diameter of the aluminum alloy hollow shape material itself by electromagnetic forming. For this reason, unlike press working or machining with a slow deformation speed, when forming a tapered body shape or forming a joining flange, the aforementioned energy absorption performance is reduced, cracks, rough skin, or residual There is little elongation.
[0029]
FIG. 1 (c), FIG. 2 (c), FIG. 3 (c), and FIG. 4 (c) show the shafts (of the hollow profile 3) of the tapered energy-absorbing members 1a, 1c, 1e, and 1g of the present invention. Flanges 2a and 2b for joining to vehicle body members are formed at both ends in the direction (3a and 3b in FIGS. 1 (b), 2 (b), 3 (b), and 4 (c)). An embodiment is shown. The formation of the joining flange is not necessarily provided at both ends in the axial direction of the energy absorbing member, but only one of them may be provided, and the point is appropriately selected according to the use conditions of the energy absorbing member. Note that the circles provided at intervals in the circumferential direction of the flanges 2a and 2b indicate bolt holes for mechanical joining or protrusions for reinforcing the flange.
[0030]
As will be described later, these flanges 2a and 2b are formed at the same time as the taper is formed by electromagnetic forming. Simultaneously with the taper formation, both ends in the axial direction of each aluminum alloy hollow material 7 as a material are expanded by electromagnetic forming. Can be formed integrally.
[0031]
Although there is a means for forming the flanges 2a and 2b by press working or machining, there is also a problem that is not practical because the working process becomes very complicated or complicated as described above. In addition, there is a high possibility that the above-described cracking, rough skin, or residual elongation that reduces energy absorption occurs during processing. Further, when the flanges 2a and 2b are separately manufactured and joined by welding or the like, the number of parts and joints are increased, so that the joint strength is lowered and the impact energy absorption performance is lowered accordingly.
[0032]
1 (c), FIG. 2 (c), FIG. 3 (c), and FIG. 4 (c), the surface of the flange (3) ) Is a flat (flat) shape in which circular flanges 2a and 2b are formed.
[0033]
Such a flange integrally formed with the hollow member 3 has remarkably higher bonding strength and higher energy absorption performance of each energy absorbing member 1 itself than the separately joined flange. Further, the energy absorbing member 1 and the other vehicle body member can be directly joined while increasing the joining area. Therefore, compared to the conventional method in which the flange is manufactured separately and the end of the energy absorbing member, the end of the vehicle body member on the joining side, and the end of the flange are joined separately, the joint strength of both Can be greatly increased. As a result, even when the energy absorbing member 1 is actually installed, it is possible to improve load energy absorbing performance due to axial crushing deformation when a large load is applied in the axial direction. Moreover, the complexity of joining with other vehicle body members can be eliminated.
[0034]
According to electromagnetic forming, the shape of the flanges 2a and 2b conforming to the shape of the joint surface of another vehicle body member to which the energy absorbing member 1a is joined or the shape of the joint surface of the vehicle body member flange can be freely molded. . For example, in Fig. 1 (c), Fig. 2 (c), Fig. 3 (c), and Fig. 4 (c), the flat surface (joint surface) shape on the body member side or the flat flange surface (joint surface) shape The above-mentioned surface is formed in the circular flange which spreads flatly.
[0035]
In this regard, if the shape of the joint surface of other body members or the joint surface of the body member flange is a curved surface shape or a flat shape that is tilted at an angle rather than a vertical direction, the aluminum alloy hollow material The flange joint surface shape can also be a curved surface shape or a shape that rises obliquely so as to conform to this.
[0036]
Here, the cross-sectional shape of the material aluminum alloy hollow material 7 and the cross-sectional shape as the energy absorbing member 1 are appropriately selected depending on the vehicle body use site and the usage mode as the energy absorbing member. However, the taper shape and the flange need to have a cross-sectional shape that can be formed by expanding the hollow material 7 by electromagnetic forming.
[0037]
That is, the rectangular cross-section tubular aluminum alloy hollow material 7b that is the material of FIG. 4 (a), the tapered energy absorbing members 1c and 1e of FIGS. 2 (b) and 3 (b), etc. In the shape or outer shape, if the corner R (angle) of the corner is too small, cracks are likely to occur at the corner when the diameter of the hollow material 3 is increased by electromagnetic forming.
[0038]
In this regard, if electromagnetic forming is possible, for example, a rectangular shape, a polygonal shape, a circular shape, an elliptical shape, or any other irregular shape that does not have a corner with a small corner R (angle) other than a circular tube. In addition to hollow materials or closed cross-sections, open-section C-shaped or U-shaped hollow shapes can also be included.
[0039]
Next, the embodiment of the energy absorbing member of the present invention shown in FIGS. 5, 6 and 7 has a convex portion that becomes a starting point of crushing when a large load such as a collision load is applied to a part of the surface of the energy absorbing member 1 (hollow material 3). In addition, a deformed portion such as a concave portion or a hole is provided.
[0040]
These deformed portions are also preferably formed integrally with the hollow material by electromagnetic forming. In the formation of the deformed portion by electromagnetic forming, as described above, unlike the formation of the deformed portion by pressing or machining with a slow deformation speed, the cracks described above are formed in the deformed portion such as a convex portion, a concave portion, and a hole, and the periphery thereof. It is less likely to cause rough skin or residual elongation.
[0041]
  The energy absorbing member 1i in FIG. 5 has a convex portion (on the surface of the aluminum alloy hollow material 3 of the tapered circular tube having the hollow portion 6 in the same manner as the energy absorbing member in FIGS. 1 (b) and 4 (b). (Protrusions) 4a, 4b are provided(However, the end flange is not formed). These convex portions (protrusions) 4a and 4b are arranged in the circumferential direction of the surface of the hollow material 3, for example, six at 60 ° intervals and four at 90 ° intervals from the center of the cross-section circle (hollow material axis). These are deformed portions provided as appropriate.
[0042]
In order to provide these deformed parts with the flanges provided at both ends by electromagnetic forming without interference during molding, and to use them as the starting point of crushing when a heavy load is applied, the length from the front surface of the hollow material 3 must be The hollow material 3 is preferably provided at a position that is about 2/3 of the axial length.
[0043]
When the energy absorbing member 1i in FIG. 5 is arranged substantially horizontally so as to extend in a direction substantially parallel to the load direction at the time of a vehicle collision, such as a bumper stay or an energy absorbing member, for example, the convex portion 4a 4b is the starting point of the crushing deformation. In other words, the convex portions 4a, 4b, etc. are formed so that the hollow material 3 is moved outward when a heavy load is applied to the axial end portion 3a on the load side (front side) of the hollow material 3 from the direction F1 at the time of a vehicle collision. Therefore, the energy absorbing member 1i (hollow material 3) serves as a starting point for the axial crushing deformation. Then, the energy absorbing performance in the axial direction of the energy absorbing member 1i is enhanced. The starting point effect of these crushing deformations is the same not only in the convex or protruding deformed portions but also in the concave or hole deformed portions described later.
[0044]
Further, in FIGS. 6 and 7, the basic structure of the energy absorbing member is the same as that of the energy absorbing member 1i of FIG. 5, and the shape of the deformed portion such as the convex portion, the concave portion, and the hole on the surface of the hollow material 3 is variously changed. Each embodiment is shown. In addition, the shape of the deformed portion such as the convex portion, the concave portion, and the hole in the present invention and the way to provide the hollow material 3 on the surface are not limited to the following modes. It is suitably selected according to the usage mode and part of the member.
[0045]
In addition, the energy absorbing members of FIGS. 6 and 7 are the tapered energy absorbing members 1a, 1c, and 1e of the present invention shown in FIGS. 1 (c), 2 (c), 3 (c), and 4 (c). In the same manner as 1g, a mode is shown in which flanges 2a and 2b for joining to a vehicle body member are formed at both ends of the hollow member 3 in the axial direction. The flanges for joining with these vehicle body members do not necessarily need to be provided at both ends in the axial direction of the hollow shape member, depending on the usage, and may be provided only on one side.
[0046]
  Among these, FIGS. 6 (a), (b) and (c) show an example in which a convex portion (projection) 4 is provided. In the energy absorbing member 1j in FIG. 6 (a), as in FIG. 5, the surface of the hollow material 3 is symmetrical in the circumferential direction.ConvexPortions 4a and 4b are provided. In the energy absorbing member 1k in FIG. 6 (b), two convex portions are arranged in two rows in the axial direction symmetrically in the circumferential direction of the surface of the hollow material 3, and a total of four convex portions 4c, 4d, 4e, 4f are provided. ing. In the energy absorbing member 1l in FIG. 6 (c), the length of the axial direction is long and symmetrical with respect to the circumferential direction of the surface of the hollow material 3.ConvexParts 4g and 4h are provided.
[0047]
In addition, along the circumference of the surface of the hollow material, spiral convex portions, ring-shaped convex portions, convex portions crossing each other in an X shape, convex portions having a relatively long axial length, and the like are spaced apart. A plurality of openings may be provided.
[0048]
Further, the energy absorbing member of FIG. 7 shows an example in which a recess or a through hole is provided on the surface of the hollow material 3. In the energy absorbing member 1m of FIG. 7 (a), a plurality of recesses or through-holes 5a, 5b are provided at intervals along the circumference of the surface of the hollow material 3. The energy absorbing member 1n shown in FIG. 7 (b) is provided with two recesses or through-holes 5c, 5d, 5e, and 5f in total, two in the circumferential direction on the surface of the hollow material 3 and two in the axial direction. ing.
[0049]
The modes of FIGS. 7 (a) and 7 (b) can be said to be a mode in which through holes are provided instead of the convex portions of FIGS. 6 (a) and 6 (b). In this regard, instead of providing the convex portion, a concave portion or a through hole may be provided, or these convex portion, concave portion and through hole may be provided in combination.
[0050]
Next, the taper shape of the hollow material 3 is actually formed, and further, the flanges at both ends of the hollow material and the deformed portions such as the above-mentioned convex portions, concave portions, and holes on the surface of the hollow material are integrally formed in the hollow material. The electromagnetic forming method will be described below.
[0051]
First, in electromagnetic forming itself, electric energy (charge) stored at a high voltage is instantaneously applied (discharged) to a current-carrying coil to form a strong magnetic field for a very short time. The work placed on the workpiece (workpiece, metal member) is subjected to strong expansion force and contraction force due to the repulsive force of the magnetic field (Lorentz force according to Fleming's left-hand rule) and plastic deformation is performed at high speed. This is a technique for plastic working or forming a workpiece into a predetermined shape.
[0052]
This electromagnetic forming is intended for forming metal members such as metal plates and pipes that are highly conductive and easily generate eddy currents, such as plate forming, tube expansion, tube contraction, and tube ends. Promising for molding. In particular, an aluminum alloy is a good electrical conductor and is a material suitable for this electromagnetic forming.
[0053]
FIG. 8 is a sectional view showing a mode in which the tapered shape of the hollow material 3, the flanges at both ends of the hollow material, and the deformed portions such as the convex portions, the concave portions, and the holes on the surface of the hollow material are simultaneously provided by electromagnetic forming.
[0054]
Here, FIGS. 8 (a) and 8 (b) show the tapered shape of the hollow material 3, and the protrusions 4a and 4b and FIG. 8 (c) shown in FIG. A mode is shown in which the through holes 5a shown in Fig. 1 are provided simultaneously by electromagnetic forming together with the flanges 2a and 2b at both ends of the hollow material.
[0055]
In FIGS. 8 (a) and (b), 28, 29, and 30 are dies, and a space-like (gap-like) molding surface 31 for forming convex portions 4a and 4b on the surface of the aluminum alloy hollow material 3 or A concave molding surface 30c is provided. These molds 28, 29, and 30 are formed so that the hollow material 3 having the same diameter in the axial direction forms a tapered shape that becomes thicker toward the right side of the figure. The opposing mold forming surfaces are formed so as to be inclined (as inclined surfaces) so that the distance between the opposing mold forming surfaces increases gradually toward the right side of the figure. The same applies to the mold 32 in FIG. 8 (c).
[0056]
Further, these molds 28, 29 and 30 are formed with circular flanges 2a and 2b which rise at a substantially right angle to the outside of the hollow material 3 at both ends of the hollow material 3 and have a flat surface. For this purpose, it has flat molding surfaces 29a and 30b that rise vertically.
[0057]
Here, in FIGS. 8 (a) and 8 (b), one of the profile end molding surfaces 28a and 30a of the molds 28, 29, and 30 is not vertical but is a flat molding surface that rises obliquely at a certain angle. It has become. As described above, this corresponds to the case where the shape of the joint surface of the other vehicle body member or the flange joint surface is not vertical but rises diagonally, and is not perpendicular to the hollow material 3 but at a certain angle. This is to create an inclined flange 2a that rises diagonally.
[0058]
8 (a) and 8 (b), the procedure for electromagnetic forming is as follows. First, an aluminum alloy material hollow material 7a (material hollow material 7a in FIG. 1) is set in the molds 28, 29, and 30. That is, the energizing coil 25 is inserted into the tube of the hollow material 3 from the end side (right side in the figure) of the hollow material 7a. Then, electric energy stored at a high voltage in an impact current generator (not shown) is instantaneously supplied to the energizing coil 25 through several tens kJ (several hundred μF, several tens kV), a capacitor 27, and a connection 26. A very strong magnetic field for a very short time is formed between the inclined molding surfaces of the opposing molds, both pipe ends, and the space (gap) molding surface 31 and the concave molding surface 30c.
[0059]
As a result, the hollow material 7a having the same diameter in the axial direction is expanded outward in the axial direction and pressed against the inclined molding surface (tapered molding surface) of the opposing mold with a strong force. As a result, the outer shape (indicated by a dotted line) of the tapered hollow material 3 whose outer diameter (diameter) gradually increases as it goes to the right side of the figure is formed.
[0060]
In addition, the taper shape is not only a linearly inclined shape whose diameter increases in the axial direction (to the right in the figure) of the hollow material 3, but is also convex outward or concave inward. The diameter-increasing taper shape is appropriately selected such that the diameter is increased by inclining in a curved line, or the diameter is increased stepwise or stepwise. These diameter-expanded taper shapes can be formed by forming the inclined molding surface of the mold into a shape corresponding to the desired diameter-expanded taper shape.
[0061]
Simultaneously with the forming of the tapered shape of the hollow portion of the hollow member, the convex portions 4a and 4b of the hollow member 3 are expanded in diameter into the gap-shaped molding surface 31 and the concave molding surface 30c of the mold, and the convex portion 4a , 4b is formed. At the same time, the diameters of the hollow material end portions 3a and 3b are expanded in the circumferential (outward) direction of the hollow material 3. The enlarged end portions 3a, 3b are pressed against the molding surfaces of the molds 28, 29, 30 with a strong force, and the flanges 2a, 2b are formed at the end portions of the hollow material 3.
[0062]
Although not shown, when a recess is formed as the deformed portion, a pipe having a shape corresponding to the recess is provided close to the surface portion of the hollow material forming the recess and used for caulking or the like. The concave portion is formed by reduced-tube electromagnetic forming that reduces the diameter.
[0063]
Next, the procedure for electromagnetic forming is the same in FIG. 8 (c). That is, the hollow material 3 having the same diameter in the axial direction is expanded outward in the axial direction, pressed against the inclined molding surface (tapered molding surface) of the opposing mold, and formed on the right side of the figure. A taper-shaped outer shape is formed which gradually increases in thickness as indicated by (indicated by a dotted line). However, in the case of FIG. 8 (c), the portion corresponding to the through hole of the hollow material 3 whose diameter has been expanded by the gap-shaped molding surface 33 of the mold 32 is the ring-shaped protrusion 32a at the tip of the gap-shaped molding surface 33. It collides and is punched in accordance with the contour shape of the ring-shaped protrusion 32a to form the through holes 5a and 5b. In the case of FIG. 8 (c), both flanges 2a, 2b at the end of the hollow material 3 are formed so as to rise vertically as shown in FIG. 7 (a).
[0064]
As described above, the aspect in which the tapered shape of the hollow material 3, the flanges at both ends of the hollow material, and the deformed portion of the hollow material surface are simultaneously provided by electromagnetic forming has been shown. However, as an integrated mode in which the molds are provided at the same time, the coils having a shape (length) corresponding to each molding site may be used, and these may be provided separately or sequentially. Alternatively, the mold may be divided separately corresponding to each molding site, and a coil having a shape (length) corresponding to each molding site may be used, and these may be provided separately or sequentially.
[0065]
Here, if the mating body member joining surface has a curved surface shape such as a saddle shape, the flanges at both ends of the hollow material are also curved according to the curved shape. For example, a flange whose surface (bonding surface) has a curved shape such as a saddle shape is formed by changing the shape of the molding surface 28a, 29b, 30a, 30b, etc. of the mold to an appropriate curved shape such as a saddle shape. it can. Further, a shape that is flat but inclined at an angle rather than in the vertical direction can be formed by inclining the molding surface of the mold with respect to the hollow material 3 at an angle instead of a right angle.
[0066]
Note that protrusions or ribs for reinforcing the flanges may be provided on the joint surfaces of the flanges, the back surface of the joint surfaces, or the like. By providing protrusions or ribs appropriately on the flange in a radial or concentric manner, the flange is reinforced. These protrusions or ribs can be easily electromagnetically formed by providing corresponding concave shapes on the molding surface of the mold. In this respect, a substantially parallel enlarged diameter portion or a tapered enlarged diameter portion may be further formed on the rear surface side of the formed flange and connected to the straight portion. By forming such an enlarged diameter portion on the rear surface side of the flange, the strength of the flange joint can be further increased. The method of providing this enlarged diameter portion can be easily controlled by adjusting the clearance between the mold and the outer diameter of the aluminum alloy hollow material.
[0067]
In these electromagnetic forming, when the end of an aluminum alloy hollow material having a relatively large diameter of 3 mm or more and a relatively large diameter of 50 mmΦ or more, such as an energy absorbing member, is subjected to pipe expansion molding, the outside of the expanded end In order to press the surface against the mold surface and form a deformed portion or a flange at the end of the aluminum alloy hollow material 3, the amount of input electric energy is preferably as large as possible, for example, 8 kJ or more.
[0068]
Incidentally, while inserting a coil into such an aluminum alloy tube end, a mold forming surface is provided close to the outside of the tube end, and electric energy is input to the coil to expand and deform the tube end. The technology to form a trumpet-shaped flange that spreads outward by pressing the outer surface side of the deformed tube end against the mold forming surface is Toshio Sano et al., “Plasticity using electromagnetic force” Processing Research "," Mechanical Technology Research Institute Report No. 150 ", published by the Mechanical Technology Research Institute in March 1990 (Chapter 6 Pipe End Molding, pp. 62-68), etc. Patent Document 1).
[0069]
However, the energy absorbing member as the object of the present invention is an aluminum alloy hollow material having a relatively thick wall of 3 mm or more and a relatively large diameter of 50 mmΦ or more. The forming of such a relatively thick and relatively large diameter aluminum alloy tube end portion is extremely difficult to form electromagnetically compared to the tube forming method for reducing the tube diameter used for caulking or the like. It was recognized and was not put into practical use until now. Also in Non-Patent Document 1, it is recognized that it is difficult to expand or form a tube by electromagnetic forming at the end of a relatively thick aluminum alloy hollow material having a relatively large diameter. The main reason for this is that the amount of input electric energy has to be reduced due to hardware restrictions such as a coil.
[0070]
Next, one usage mode when the energy absorbing member of the present invention is used for a bumper module in a vehicle body will be described with reference to FIGS. Figure 9 shows the bumper structure in front view. In FIG. 9, first, 10 is a bumper cover, 11 is an impact absorbing material appropriately configured with foamed foam material, 12 is a bumper reinforcement, 13 is a stay, 14 is a vehicle body side member, and 1i is the tapered energy of the present invention. Fig. 6 is an absorbent member (the embodiment of Fig. 6 (a)). These members are arranged in the order of description in the longitudinal direction of the vehicle body (the left side in the figure is the front).
[0071]
The rear flange surface 16a of the bumper reinforcement 12 and the front flange 13a of the stay 13, the rear flange 13b of the stay 13 and the front flange 2a of the energy absorbing member 1i, the rear flange 2b of the energy absorbing member 1i, and the front surface of the side member 14 The flanges 14a are joined to each other by means of welding or mechanical coupling means 20 such as bolts, nuts, rivets or the like.
[0072]
The bumper reinforcing member 12 includes, for example, a front flange 15 and a rear flange 16 that are provided substantially in parallel in the longitudinal direction of the vehicle body, and left and right webs 17 and 18 that are provided substantially in parallel to connect the flanges. It is composed of an integral aluminum alloy hollow extruded profile. The bumper reinforcing material 12 may be a steel hollow material, but it is preferable from the viewpoint of weight reduction that it is made of an aluminum alloy hollow material and also an aluminum alloy hollow extruded shape. Reference numeral 19 denotes a reinforcing middle rib that is selectively provided, and has a substantially rectangular shape with a cross-sectional shape of a sun.
[0073]
Similarly to the energy absorbing member 1i, the stay 13 is made of an aluminum alloy hollow material. When the flanges 13a and 13b are integrally formed at the end of the stay by electromagnetic forming, the energy of the present invention is substantially reduced. It becomes an absorbing member. In the present invention, the stay 13 may be a conventional aluminum alloy hollow material or steel stay. Further, the stay 13 may be an aspect of the energy absorbing member of the present invention, and the energy absorbing member 1i may be omitted.
[0074]
Furthermore, since the side member 14 requires particularly high strength, it is preferable that the side member 14 is made of steel as usual. For this reason, it is preferable that the front flange 14a is also a steel flange integrated with the end of the side member 14 by welding as usual.
[0075]
In the embodiment of the present invention in FIG. 9, the energy absorbing member 1i has an axial direction relative to the collision load direction from the left side of the figure (front of the vehicle body) so that the base becomes thicker with respect to the collision load from the front surface. Each of the hollow materials has a tapered shape in which the outer diameter gradually increases toward the rear side with respect to the load direction. For this reason, the load energy absorption performance can be enhanced in terms of the moment of inertia of the cross section with respect to the collision load from the front surface. Moreover, even if the collision load is input at an angle slightly inclined with respect to the length direction, the load energy absorption performance can be ensured.
[0076]
Further, the flanges 2a and 2b of the energy absorbing member 1i have a flat shape that rises vertically corresponding to the shape of the rear flange 13b of the stay 13 and the front flange 14a of the side member 14. The hollow material 3 is integrally formed. For this reason, the energy absorbing member 1i and the stay 13 and the side member 14, which are other vehicle body members, can be directly joined through the respective flanges while increasing the joining area. Therefore, it is possible to significantly increase the joining strength of the energy absorbing member 1i as compared with the conventional method in which these flanges are manufactured separately and joined separately. Further, the energy absorbing member 1i has convex portions 4a and 4b that are the starting points of the crushing deformation.
[0077]
As a result, the load energy transmitted from the front of the vehicle body through the bumper cover 10 in the axial direction (vehicle longitudinal direction) at the time of the vehicle collision is crushed and deformed in the axial direction of the stay 13 and in the axial direction of the energy absorbing member 1i. Due to the deformation, the energy absorption performance can be greatly improved. Further, since it can be directly joined to other vehicle body members via the flange of the energy absorbing member 1i, even if only the energy absorbing member 1i is broken due to the crushing deformation at the time of the vehicle body collision, only the energy absorbing member 1i is attached. It can be easily removed and a new energy absorbing member can be easily attached. These effects can be applied to the stay 13 when the stay 13 is an energy absorbing member.
[0078]
FIG. 10 is a plan view showing only the main part of the bumper structure of FIG. However, in FIG. 10, the bumper reinforcing member 12 has both end portions 12a and 12b which are not linear in the longitudinal direction (vehicle width direction) as shown in FIG. For this reason, the two stays 13 for supporting the bumper reinforcing material 12 are arranged at intervals on the rear surfaces of both end portions 12a and 12b inclined to the rear side of the vehicle body of the bumper reinforcing material 12, respectively.
[0079]
Therefore, each front flange 13a of the stay 23 has a flat shape inclined in each direction in accordance with the shape of the rear surface of both end portions 12a, 12b of the bumper reinforcing member 12. Then, the bumper reinforcing material 1 is supported from the rear surface side in the vehicle front-rear direction via the front flange 13a with the tube axis direction (hollow profile shaft direction) as the vehicle front-rear direction (horizontal direction).
[0080]
When the front flange 13a needs to have such an inclined shape that is difficult to form normally, the stay 13 is made of an aluminum alloy hollow material as in the case of the energy absorbing member 1i of the present invention. It is advantageous to integrally form the flange 13a and the rear flange 13b at the stay end by electromagnetic forming. The structure of each member and the connection structure other than this are the same as those in FIG.
[0081]
  As an aluminum alloy that satisfies the required characteristics as the energy absorbing member (hollow material) of the present invention, the AA to JIS 5000 series, 6000 series, 7000 series, etc. It is a high general-purpose alloy that is selected from tempered aluminum alloys. However, among them, in particular, Al-Zn-Mg-based or Al-Zn-Mg-Cu-based 7000-based aluminum alloy extruded hollow shapes, which have tempering such as T5, T6, T7 (especially artificial aging) (Treated) aluminum alloy extruded hollow profile is preferredYes.
[0082]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the aluminum alloy energy absorption member for vehicle bodies which provided the taper shape or the flange for joining integrally, etc. can be provided, without reducing energy absorption performance. For this reason, the weight reduction of an energy absorption member and the vehicle body itself can be accelerated | stimulated, and the use of an aluminum alloy material further expands, and industrial value is great.
[Brief description of the drawings]
FIG. 1 shows an embodiment of the energy absorbing member of the present invention, FIG. 1 (a) is a material tubular hollow material, FIG. 1 (b) is a circular tubular energy absorbing member, and FIG. 1 (c) is a flanged circular tube. It is a perspective view which shows each energy absorption member.
2 shows another embodiment of the energy absorbing member of the present invention, FIG. 2 (a) is a material circular hollow material, FIG. 2 (b) is a polygonal energy absorbing member, and FIG. 2 (c) is a flanged multi member. It is a perspective view which shows each square energy absorption member.
3 shows another embodiment of the energy absorbing member of the present invention, FIG. 3 (a) is a material tubular hollow material, FIG. 1 (b) is a rectangular energy absorbing member, and FIG. 1 (c) is a rectangular energy with flange. It is a perspective view which shows each absorption member.
FIG. 4 shows another embodiment of the energy absorbing member of the present invention, FIG. 3 (a) is a rectangular hollow material, FIG. 1 (b) is a circular energy absorbing member, and FIG. 1 (c) is a flanged circle. It is a perspective view which shows each tubular energy absorption member.
FIG. 5 is a perspective view showing another embodiment of the circular tubular energy absorbing member of the present invention and showing an embodiment provided with a deformed portion.
6 shows another embodiment of the flanged tubular energy absorbing member of the present invention, and FIGS. 6 (a), 6 (b), and 6 (c) are perspective views showing an embodiment in which different deformation portions are provided. FIG. .
FIG. 7 shows another embodiment of the flanged tubular energy absorbing member of the present invention, and FIGS. 7 (a) and 7 (b) are perspective views showing an embodiment in which different deformation portions are provided.
FIGS. 8A, 8B, and 8C are cross-sectional views showing a mode in which different flanges and deformed portions are provided, respectively, illustrating a mode of manufacturing the energy absorbing member of the present invention by electromagnetic forming. FIGS.
FIG. 9 is a front view showing a usage mode of the energy absorbing member of the present invention for a bumper.
FIG. 10 is a plan view showing a usage mode of the energy absorbing member of the present invention for a bumper.
FIG. 11 is a perspective view showing a conventional tapered automobile energy absorbing member.
[Explanation of symbols]
1: energy absorbing member, 2: flange, 3: hollow material, 4: convex part, 5: hole,
6: Hollow part, 7: Material hollow shape,

Claims (4)

Energy absorption that consists of an aluminum alloy extruded hollow material and is joined to the body member so that the axial direction of the hollow material becomes the load application direction, and then collapses in the axial direction of the hollow material when a load is applied to absorb the load energy The hollow material has a tapered shape in which the outer diameter of the hollow material increases toward the rear side in the axial direction with respect to the load, and the tapered shape is formed by expanding the hollow material by electromagnetic forming, and the hollow At the end in the material axis direction, a flange is formed that has a joint surface shape that matches the shape of the joint surface of the vehicle body member and extends outward. The flange is expanded at the end in the hollow material axis direction by electromagnetic forming. The flange is pressed against the molding surface and formed integrally with the hollow material. The flange is joined to the body member with the surface opposite to the surface pressed against the mold as a joining surface. Is Vehicle body energy absorbing member, characterized in that.   The vehicle body energy absorbing member according to claim 1, wherein a deformed portion serving as a starting point of collapse when the load is applied is provided on the surface of the hollow material.   The vehicle body energy absorbing member according to claim 2, wherein the deformable portion is provided by electromagnetic forming.   The energy absorbing member for a vehicle body according to any one of claims 1 to 3, wherein the energy absorbing member is disposed in a bumper.

Images