Technical field
[0001]
　The present invention relates to a shock absorbing member for absorbing an impact load applied in the axial direction by a periodic buckling.
Background technique
[0002]
　Cars and railway, the transportation equipment such as vessels, shock-absorbing member is used. The shock absorbing member receives an impact load can absorb the energy of collision by deforming at the time of collision, the occupant safety can be secured accordingly. Such shock-absorbing member, for example, a frame member and crash boxes of the car.
[0003]
　Figure 1 is a perspective view schematically showing the arrangement of the frame member and crash boxes in motor vehicles. As shown in the figure, the vehicle side, the front side member 2, the rear side members 3 and the side sill 7 is positioned. These members are all provided along the longitudinal direction of the automobile. Front side member 2 to the front of the vehicle side, the rear side member 3 at a rear portion of the vehicle side, the side sill 7 is positioned in the middle portion of the vehicle side.
[0004]
　In the middle portion in the longitudinal direction of the automobile, the floor (floor) is provided. Its floor, floor cross member (4, 4 ') are arranged, a floor cross member (4, 4') extends in the width direction of the automobile.
[0005]
　Crash box (1a, 1b) are disposed at the distal end of the frame comprised of frame members described above. More specifically, the first crash box 1a is provided at the front end of the front side member 2, the second crash box 1b is provided at the rear end of the rear side members 3.
[0006]
　These front side member 2, the rear side members 3, frame member such sill 7 and the floor cross member (4, 4 '), and the crash box (1a, 1b), the cases are loaded into their axially during a collision is there. In this case, by buckling deformation thereof member such contracts axially like bellows, to absorb the impact load.
[0007]
　Such impact absorbing member can be made by bending Ya lap welding a metal plate which is the material. Shock absorbing member made of a metal plate is tubular. That, is closed shape in the axial direction and a section perpendicular. Therefore, the shock absorbing member, its interior is hollow.
[0008]
　Relates shock absorbing member that absorbs the impact load by periodic buckling, various proposals have been made.
[0009]
　Patent Document 1, the crash box is described. Its crash box, in addition to the members forming the hollow section, comprising a middle plate which extends horizontally so as to partition the hollow area up and down in the vertical direction near the center of the hollow cross-section. By providing the intermediate plate, the crash box without collapse buckled on impact, they are to be inhibited from bending. In that configuration example, member (first member, a second member) for forming the hollow section a third member that constitutes a and the intermediate plate is the plate thickness of these metal plates are both the same.
[0010]
　Also Patent Document 2, the crash box is described. Its crash box is disposed between the front side member and the bumper member of the vehicle front side. Further, the crash box comprises a cylindrical box body, and a reinforcement which connects the pair of opposing wall portions facing each other of the box body. By providing the reinforcement in the hollow portion of the thus box body, to set the performance of the crash boxes to the performance of the target, and that it can set the desired performance depending on the shape and size of the reinforcement. In Patent Document 2, the thickness of the metal plate used in the box main body and the reinforcement, has not been studied at all.
CITATION
Patent Document
[0011]
Patent Document 1: JP 4766422 JP
Patent Document 2: Japanese Patent No. 5168477
Summary of the Invention
Problems that the Invention is to Solve
[0012]
　Impact absorbing member, as described above, may be fabricated from a metal plate. In this case, the shape of the axial cross section perpendicular, to close and, for example, a polygonal shape. Therefore, the shock absorbing member, its interior is hollow.
[0013]
　In the shock absorbing member made from such a metal plate, a method of ensuring the axial crush performance, if the cross-sectional shape is rectangular, the reference width Wp of the linear portion of the short side (described later FIG. 2 (b), the unit: mm) and can be adopted a method of reducing the ratio of the thickness t (mm) (Wp / t). In this way, shortens the seat 屈波 length by reducing the Wp / t, it is possible to increase the absorption energy of the shock absorbing member.
[0014]
　Further, a method of increasing the total cross-sectional area of ​​the ridge line portion connecting the sides and edges can be adopted. In this way, buckling behavior can be stabilized with the buckling load is increased, it is possible to increase the absorbed energy of the shock absorbing member.
[0015]
　On the other hand, Patent Documents 1 and 2, along the hollow portion in the axial direction, it is described that provide a metal plate such as the middle plate and the reinforcement. Hereinafter, the metal plate to form the hollow portion is also referred to as "body", the metal plate material is provided along the hollow portion in the axial direction is sometimes referred to as the "intermediate plate".
[0016]
　Thus, by forming the shock-absorbing member in the body and the middle plate, it is possible to assistance intermediate plate absorption of energy by the body. Therefore, it is possible to increase the absorbed energy of the shock absorbing member, for example, it is effective in the impact-absorbing member of large vehicles.
[0017]
　If the shock-absorbing member constituting the main unit and intermediate plate, mainly body responsible for the absorption of energy, supplementarily have intermediate plate play. For this reason, the thickness of the intermediate plate is thinner than the thickness of the body. Alternatively, as shown in the configuration example of Patent Document 1, the thickness of the intermediate plate is the same as the thickness of the body.
[0018]
　Incidentally, in the automobile, from the viewpoint of fuel efficiency, weight reduction of the parts is required. Therefore, in the shock absorbing member, it is lightweight are required while ensuring absorption energy.
[0019]
　The present invention has been made in view of such problems, and an object thereof is to provide a shock-absorbing member capable of weight saving while ensuring absorption energy.
Means for Solving the Problems
[0020]
　The present inventors, the shock absorbing member, a method for weight reduction while ensuring the absorption energy was studied intensively.
[0021]
　To reduce the weight of the impact-absorbing member, it is conceivable to reduce the thickness of the body. However, if generally thinner the thickness of the body, when the impact absorbing member receives an impact load, deformation is dominated by out-of-plane deformation (closed deformation towards the outside of the cross section), the impact absorption energy is reduced .
[0022]
　Results of study of the present inventors, by appropriately designing the plate in a shock-absorbing member, the phase at both sides of the intermediate plate is to generate a different buckling, reduce the amplitude of the deformation can be shortened wavelength It was found that there. Thus, deformation of the case where the shock absorbing member receives an impact load becomes buckled dominant, so that not only the absorption energy of the impact-absorbing member is increased, to increase the absorbed energy per unit mass it can. Therefore, even when the thin plate thickness of the main body, it is possible to ensure the absorbed energy, it was found that it is possible to perform weight saving while ensuring the absorption energy.
[0023]
　The present invention was made based on the above findings, it provides the followings.
[0024]
　[1] There shock absorbing member for absorbing an impact load applied in the axial direction, the shock absorbing member is made of a metal plate, and the body shape in the axial direction perpendicular cross-section is polygonal, is composed of a metal plate, and a middle plate provided along the axial direction in the hollow portion in the body, the polygonal shape of the body has a pair of long sides facing each other, the intermediate plate is , are joined to each long side of the polygonal shape of the body, the thickness of the body is not less 2mm or less, the impact-absorbing member thickness in said plate and wherein the thicker than the plate thickness of the body.
[0025]
　[2] impact absorbing member of the [1] in which the thickness of said body, characterized in that it is 2.3mm or less.
[0026]
　[3] the thickness of the body t1 (mm), the impact absorbing member of the [1] or [2] to the thickness of the insertion plate t2 (mm) is characterized by satisfying the following formula (1).
　　1.3 × t1 ≦ t2 ··· (1 )
[0027]
　[4] the pair of long sides are both either shock absorption of the width W1 of the long sides (mm) is characterized by satisfying the following formula (2) [1] to [3] Element.
　　W1 / t1 ≧ 20 ··· (2 )
[0028]
　[5] The main body is made of one metal plate, the mid plate, the joined by welding superimposed on each long side of the polygonal shape of the body, the pair of long sides are both the in satisfy the long side width distance along the direction d1a of (mm) and d1b (mm) satisfies the following equation (3) from the thickness center in said plate to the end points of the long side in the width direction of the center of the plate any of the shock absorbing member of [1] to [4], characterized by.
　　0.5 ≦ d1a / d1b ≦ 2 ··· (3)
[0029]
　[6] The main body includes a first metal plate comprising a portion of the polygonal shape, and the composed of the second metal plate formed with the remainder of the polygonal shape, the first metal plate and the second metal plate, wherein the welded overlapped with said intermediate plate at each long side of the polygonal shape, the pair of long sides are both thickness center in said plate in the widthwise central position in said plate distance along the width direction of the long side to the end point of the long sides of the first metal plate from d3a (mm), and, from said thickness center in said plate in the widthwise central position in said plate any of the above [1] to [5], wherein the distance along the width direction of the long side to the end point of the long sides of the second metal plate d3b (mm) satisfies the following equation (4) Kano shock absorbing member.
　　0.5 ≦ (d3a / t1a) / (d3b / t1b) ≦ 2 ··· (4)
　However, t1a (mm) is the thickness of the first metal plate, t1b (mm) is the second metal plate the plate is the thickness.
[0030]
　[7] the metal plate constituting the body has a tensile above, wherein the strength is 780MPa or more steel sheets [1] one of the shock absorbing member to [6].
[0031]
　[8] one of the shock absorbing member of [1] to [7] Young's modulus of the metal plate constituting the intermediate plate is characterized in that at least 180 GPa.
[0032]
　[9] car class shoe box, or a front side member, the rear side member, sill, or any of the shock absorbing member of [1] to [8], wherein the floor is cross member.
Effect of the Invention
[0033]
　Impact-absorbing member of the invention, the buckling deformation with different phases occurs on both sides of the intermediate plate, the wavelength becomes shorter with the amplitude of the variations is reduced. Thus, not only the absorption energy of the impact-absorbing member is increased, it is possible to increase the absorbed energy per unit mass. Therefore, even when the thin plate thickness of the main body, it is possible to ensure the absorbed energy, it is possible to perform weight saving while ensuring the absorption energy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034]
[1] Figure 1 is a perspective view schematically showing the arrangement of the frame member and crash boxes in motor vehicles.
FIG. 2 is a schematic diagram showing a configuration example of the shock absorbing member of the present invention, FIG. (A) is a front view, FIG. (B) is an A-A sectional view.
FIG. 3 is a diagram showing the relationship between the absorption energy per thickness and unit weight of the body in the case of changing the thickness of the intermediate plate.
[4] FIG. 4 is a sectional view showing another structure in which the body is made of one metal plate, FIG. (A) may be linear portion of the middle plate relative to the long side of the body It shows a configuration example which is non-perpendicular Te, FIG. (b) shows a configuration example body is a trapezoid.
FIG. 5 is a sectional view showing a configuration example in which the body consists of two metal plates schematically.
FIG. 6 is a diagram showing the relationship between the load of Examples and displacement (axial displacement).
[7] FIG. 7 is a diagram showing a displacement in the X direction in the long side surface of the shock absorbing member in Comparative Example 1 and Comparative Example 2.
[8] FIG. 8 is a diagram showing a displacement in the X direction in the long side surface of the shock absorbing member of the present invention Example 1 and Comparative Example 2.
DESCRIPTION OF THE INVENTION
[0035]
　Hereinafter, the shock absorbing member of the present embodiment will be described with reference to the drawings.
[0036]
　Figure 2 is a schematic diagram showing a configuration example of the shock absorbing member of the present invention, (a) is a front view, (b) is a sectional view taken along A-A. Shock absorbing member 10 shown in FIG. 2 includes a main body 20, and a middle plate 30.
[0037]
　Body 20, the shape of the axially perpendicular cross-section is polygonal. Body shown in FIG. 2 (b) 20, the cross-sectional shape is a square shape. Body 20 is closed cross-sectional shape, a tubular shape.
[0038]
　Each side of the polygonal shape is a linear shape, is connected with the adjacent sides and an arc. Also, polygonal shape has a pair of long sides facing each other. Here, the long side of each side of the polygonal shape refers to the longest side. The polygonal shape of the body 20 shown in FIG. 2 (b), the first long side 20a and a second long side 20b correspond to a pair of long sides. First long side 20a and a second long side 20b as compared to their non-edges, long.
[0039]
　In the long sides, the metal plate need not be continuous, may include a connection part in the middle. In FIG. 2 (b), although the second long side 20b made of continuous metal plate, the first long side 20a, the metal plate is not continuous on the long sides, including the connecting portion on the way. Polygonal present invention may be in such a configuration.
[0040]
　Intermediate plate 30 is provided along the axial direction in the hollow portion of the main body 20. Its mid-plate 30, the edge portion of the two portions to be joined with the main body 20, and a linear portion provided between them edges, the edges and the straight portions, respectively connected by arcs It is.
[0041]
　Further, the middle plate 30 is joined to the long sides of the polygonal shape of the body (20a, 20b). Specifically, it provided from the middle of the first long side 20a of the polygonal shape body 20 formed to reach the middle of the second long side 20b. The shock absorbing member shown in FIG. 2 (b), both edges of the middle plate 30, in the middle of the second long side 20b of the intermediate and polygonal shape of the first long side 20a of the polygonal shape, is superimposed with the main body 20 It is welded.
[0042]
　The shock absorbing member of the present embodiment can be adopted such a configuration example, the thickness of the body 20 is at 2.3mm or less, the thickness of the middle plate 30 is thicker than the thickness of the body 20.
[0043]
　By the thickness of the middle plate 30 thicker than the thickness of the body 20, suppressing the out-of-plane deformation of the body when an impact load is applied to the impact absorbing member, it is possible to produce a continuous buckling it can be thinned the thickness of the body 20, to increase the absorbed energy.
[0044]
　Figure 3 is a diagram showing the relationship between the absorption energy per thickness and unit weight of the body in the case of changing the thickness of the intermediate plate. If the thickness of the middle plate of FIG. 3 is 2 mm, it was carried out according to the test in the present invention of the embodiment described later. Further, the plate thickness of the middle plate of 1 mm, was carried out according to the test in Comparative Example 1 of the Examples below. For no intermediate plate, the test, without providing a middle plate was carried out in accordance with Comparative Example 2 described in Examples below. In any case, and the thickness of the body was varied in the range of 0.8 ~ 2.0 mm. It absorbed energy per unit mass shown in FIG. 3 (no unit), the absorption energy (kJ / kg) per unit mass, the thickness of the body and 0.8 mm, per unit mass of the case without the intermediate plate it is obtained by dividing the absorbed energy (kJ / kg). That is, the thickness of the body and 0.8 mm, the absorbed energy per unit mass of the case without the intermediate plate as a reference, shown as relative values.
[0045]
　From Figure 3, the absorbed energy per unit mass is seen to vary with the thickness of the intermediate plate. Specifically, as the thickness of the intermediate plate is thick, the absorbed energy per unit mass increases. That is, by increasing the thickness of the intermediate plate, it is possible to improve the absorbed energy per unit mass.
[0046]
　However, since the mass of the plate thickness of the intermediate plate increases the shock-absorbing member is increased, it may be determined the thickness of the intermediate plate and the main body in consideration of the balance of the improvement of the mass increased energy absorption. Considering the balance of the improvement in weight gain and absorbed energy, the thickness t1 of the main body, the thickness of the intermediate plate t2 may satisfy the following equation (1).
[0047]
　　１．３×ｔ１≦ｔ２　・・・（１）
[0048]
　Subsequently, the deformation behavior of the impact-absorbing member of the present embodiment will be described in comparison with the deformation behavior of the conventional impact absorbing member.
[0049]
　Shock absorbing member of the present embodiment, the periodic buckling as contracts axially like bellows, to absorb the impact load. More specifically, if the impact-absorbing member shown in FIG. 2, the long side of the body, including the junction between the middle plate (overlay weld) (plane, code: 20a, 20b) is, the long side (the surface ) and by deforming such displacement occurs in a direction perpendicular (X-direction in FIG. 2), deformed into a bellows shape.
[0050]
　Figure 7 is a diagram showing a displacement in the X direction in the long side surface of a conventional shock absorbing member is a diagram showing the test results of Comparative Example 1 described later. In Comparative Example 1, 0.8 mm plate thickness of the main body, and 1.0mm of thickness of the intermediate plate, the plate thickness Metropolitan plate thickness of the main body and the intermediate plate has the same level. Figure 7 also shows the test results of Comparative Example 2. Comparative Example 2 is an example in which not provided intermediate plate. X direction displacement shown in FIG. 7 is a displacement at the long side surface, respectively show the two sides of the middle plate (P1 and P2 in FIG. 2 (a)) Of the long side surface.
[0051]
　As shown in FIG. 7, in the conventional shock absorbing member (Comparative Example 1), the same phase in the waveform due to the displacement on both sides of the middle (the period of buckling) of plates (P1, P2). Here, in the conventional shock absorbing member, the thickness of the middle plate than the plate thickness of the main body, a thin or comparable. Therefore, rigidity of the intermediate plate is lower than that rigidity of the body, resulting in the same phase waveform by displacement on both sides of the intermediate plate.
[0052]
　Further, the middle plate is deformed so as to follow the long side surface of the body. Therefore, in the conventional shock absorbing member, if provided with no intermediate plate (Comparative Example 2 of FIG. 7), the wavelength is comparable. As a result, the absorbed energy by providing the intermediate plate is increased, the absorption energy per unit mass is not substantially changed.
[0053]
　In Comparative Example 1, a plate thickness 1.0mm plate thickness of the body is 0.8 mm, the middle plate, strictly speaking, the thickness of the middle plate is slightly thicker than the thickness of the body. Deformation behavior of the thus the plate thickness of the intermediate plate is about the same as the thickness of the body, compared though not test results, conventional shock absorbing member, i.e., the thickness of the intermediate plate is a plate thickness of the main body the thickness of the case and the middle plate thin Te is the same as the case is the same as the thickness of the body.
[0054]
　Figure 8 is a diagram showing a displacement in the X direction of the impact-absorbing member according to the present invention, showing a test result of the present invention Example 1 below. In the present invention Example 1, 0.8 mm plate thickness of the main body, and 2.0mm of thickness of the intermediate plate, the plate thickness of the intermediate plate was thicker than the body. Figure 8 also shows the test results of Comparative Example 2. Comparative Example 2 is an example in which not provided intermediate plate. X direction displacement shown in FIG. 8 is a displacement at the long side surface of the main body, are respectively the sides of the middle plate (P1 and P2 in FIG. 2 (a)) Of the long side surface.
[0055]
　As shown in FIG. 8, the impact-absorbing member of the present embodiment, the opposite phase on both sides of the intermediate plate is a part of the waveform caused by the displacement. This is because the shock absorbing member of the present embodiment, the thickness of the intermediate plate from thicker than the thickness of the body, due to the rigidity of the intermediate plate is high.
[0056]
　Therefore, the middle plate, but is deformed so as to follow the long side surface of the body, the deformation is greatly reduced. In this case, the long side surfaces of the body, it is possible to deform independently on both sides of the intermediate plate. As a result, part of the long side surface of the body is deformed so as to be opposite phase on both sides of the intermediate plate. Further, if provided with no intermediate plate compared with (Comparative Example 2 of FIG. 8), the wavelength becomes shorter with the amplitude of the waveform caused by the displacement becomes smaller. These shock absorbing member of the present embodiment, not only the absorption energy increases, it is possible to increase the absorbed energy per unit mass.
[0057]
　Thus, the shock absorbing member of the present embodiment, the absorbed energy per unit mass can also be increased, even when the thin plate thickness of the main body, it is possible to secure the absorbed energy. Therefore, it is possible to perform weight saving while ensuring the absorption energy.
[0058]
　Is satisfied the thickness t2 of the plate thickness t1 and the intermediate plate 30 of the body 20 (1), i.e., if the plate thickness t2 is (1.3 × t1) or more, the rigidity of the middle plate relative to the body It can be secured. Therefore, deformation behavior as described with reference to generate Figure 8, not only the absorption energy increases, the absorbed energy per unit mass can also be increased. From the viewpoint of improving the effect of increasing the absorption energy per unit mass, thickness t2 is preferably a (1.4 × t1) or more, and more preferably, (1.5 × t1) or more.
[0059]
　On the other hand, the effect of thickening the thickness of the middle plate has a tendency to saturate the plate thickness t2 is greater than (8 × t1). Therefore, the plate thickness t2 is preferably a (8 × t1) or less, and more preferably not more than (5 × t1).
[0060]
　As described with reference to FIG. 3, as the thickness of the body is thin, a large effect of improving the energy absorbed per unit mass by a plate thickness increase of the middle plate. From the viewpoint of weight reduction of parts, thickness of the body is preferably 2.3mm or less, more preferably 2.0mm or less, more preferably 1.6mm or less.
[0061]
　Body shape in the axial direction perpendicular cross-section is polygonal. For example, it can be a rectangular shape as in the configuration example described above. If a square, rectangular or trapezoidal shape may be a parallelogram. Further, it is possible to polygonal shape other than rectangular shape, for example, may be a hexagonal shape.
[0062]
　A pair of long sides (20a, 20b) is (see FIG. 2 (b)) Both the long sides of the width W1 (mm) preferably satisfies the following formula (2). In the present embodiment, "the long sides of the width W1" refers to the length of the straight portion excluding the ridge portion.
[0063]
　　W1 / 20 · · · t1 ≦ (2)
[0064]
　A pair of long sides of the body are both middle plate is joined. Their width W1 of the long sides, both, as long as 20 or more as a percentage of the thickness t1 of the body (W1 / t1), independently on both sides of the middle plate when the long side surface of the body is deformed width for deformation can be secured sufficiently. Therefore, the effect of increasing the absorption energy per unit mass of the present embodiment is stable. From the viewpoint of more stable its effect, W1 / t1 is more preferably set to 25 or more.
[0065]
　On the other hand, W1 / t1, when more than 200, the effect of increasing the absorption energy per unit mass is saturated. Therefore, W1 / t1 is preferably set to 200 or less.
[0066]
　Joining the body and the intermediate plate, without the main body and the intermediate plate are separated at the time of collision, as far as possible deformation integrally, can be carried out by various methods, for example, can be employed lap welding. In this case, for example, it can be employed spot welding in continuous welding or a predetermined pitch.
[0067]
　Body, for example, can be made from a single metal plate. In this case, bent to the metal plate section is polygonal, as shown in FIG. 2 may be welded by superposing both ends with the intermediate plate.
[0068]
　Together with the way the body 20 is made of one metal plate, the case of joining by lap welding, a pair of long sides (20a, 20b) are middle plate in both the width direction of the center of the middle plate 30 30 thickness center C of the long sides (20a, 20b) long sides (20a, 20b) to both end points in the width direction along a distance d1a of (mm) and d1b (mm) that satisfies the following equation (3) It is preferred.
[0069]
　　０．５≦ｄ１ａ／ｄ１ｂ≦２　・・・（３）
[0070]
　For d1a (mm) and d1b (mm), the linear portion of the middle plate will be described with reference to the exemplary configuration is an exemplary configuration and the main body is a non-vertical trapezoidal with respect to the long side of the body.
[0071]
　Figure 4 is a cross-sectional view showing another configuration example of a case made of body single metal plate, (a) shows the configuration linear portion of the intermediate plate is non-perpendicular to the long side of the body examples, (b) are configuration examples body is a trapezoid. In the configuration example shown in (a), the cross-sectional shape of the main body 20 has a rectangular shape. On the other hand, the middle plate 30, the linear portion is non-perpendicular to the long side of the body. In the configuration example shown in (b), the main body is trapezoidal, the middle plate 30, the linear portion is non-perpendicular to the long side of the body.
[0072]
　FIG. 2 (b), the as shown in FIG. 4 (a) and 4 (b), the distance d1a and distance d1b, the long sides of the plate thickness center C of the middle plate 30 in the width direction of the center of the middle plate 30 (20a, 20b) is the distance from one end to the other end point of. Such distance d1a and distance d1b are both a distance in the width direction of the long side (20a, 20b). In other words, the distance d1a and distance d1b from thickness center C of the middle plate 30 in the width direction of the center of the middle plate 30 long sides (20a, 20b) a perpendicular line is drawn to the thickness center line of the perpendicular line and the length sides (20a, 20b) is a linear distance from the intersection of the thickness center line to the end points of the long side (20a, 20b).
[0073]
　In the present embodiment, "the width direction of the center of the middle plate" means the center position in the width direction of the linear portions among the intermediate plate. Further, in the present embodiment, "endpoint of the long side" means the end point of the straight portion excluding the ridge portion.
[0074]
　(3) By satisfying equation distance about the long sides of the body (d1a, d1b) are both be suitable, the body long sides face each independently for deforming on both sides of the middle plate when the deformation width can be sufficiently secured. Therefore, the effect of increasing the absorption energy per unit mass of the present embodiment is stable.
[0075]
　The body can also be produced by lap welding two metal plates, in this case, it may be different thickness of two metal plates.
[0076]
　Figure 5 is a sectional view showing a configuration example in which the body consists of two metal plates schematically. Body shown in FIG. 5 20 is composed of a first metal plate 21 second metal plate 22.. The first metal plate 21 becomes part of the polygonal shape, the second metal plate 22, the remainder of the polygonal shape. In other words, the main body 20, in the middle of each long side (20a, 20b), i.e., at the site where the middle plate 30 is welded, is divided into a first metal plate 21 into two second metal plate 22 that. Therefore, the site to be lap welding, the first metal plate 21 and the second metal plate 22 of the main body is welded in a state of being superimposed with the middle plate 30.
[0077]
　Thus the body is made of two metal plates were welded overlapped, and, if the plate thickness of the two metal plates are different, in order to obtain the deformation behavior of the embodiment described above, two metal plates it is necessary to satisfy any thickness may (1) of. Further, the thickness of the middle plate t2 is for any two metal plates of the body, preferably at (1.4 × t1) or more, that is (1.5 × t1) or more more preferable. On the other hand, the thickness of the middle plate t2 is for any two metal plates of the main body, (8 × t1) is preferably in the range or less, and more preferably not more than (5 × t1). Further, the main body, both of the thickness of the two metal plates is preferably at 2.3mm or less, more preferably 1.6mm or less.
[0078]
　If made of two metal plates which body is welded overlapped, a pair of long sides (20a, 20b) are both distance d3a (mm) and the distance d3b (mm) satisfies the following equation (4) preference is. The distance d3a is the distance from the thickness center of the middle plate 30 in the width direction of the center of the middle plate 30 to the end point of the long side (20a, 20b) of the first metal plate 21. The distance d3b is the distance from the thickness center of the middle plate 30 in the width direction of the center of the middle plate 30 to the end point of the long side (20a, 20b) of the second metal plate 22. These distances d3a and distance d3b are both a distance in the width direction of the long side (20a, 20b) (see FIG. 5).
[0079]
　　0.5 ≦ (d3a / t1a) / (d3b / t1b) ≦ 2 · · · (4)
[0080]
　By satisfying the expression (4), the distance related to the long sides of the body (d3a, d3b) are both be suitable, the body long sides face each independently for deforming on both sides of the middle plate when the deformation width can be sufficiently secured. Therefore, the effect of increasing the absorption energy per unit mass of the present embodiment is stable.
[0081]
　Metal plate used in the main body is not particularly limited. With a tensile strength 780MPa or more steel as the body, when used as an impact absorbing member for a vehicle, it is advantageous from the intensity surface, the use of higher tensile strength 980MPa of the steel sheet is further advantageous.
[0082]
　Metal plate used in the intermediate plate is not particularly limited. With Young's modulus 180GPa or more metal plates as the middle plate, preferably in suppressing out-of-plane deformation of the body.
[0083]
　Shock absorbing member of the present embodiment can be used as automobile and railway, the shock absorbing member in the transportation equipment, such as a ship. More specifically, in the case of using as an impact-absorbing member of a motor vehicle, it can be used to crush box or frame member. For frame member, front side member, the rear side member can be used for the side sill or floor cross member.
Example
[0084]
　To confirm the effects of the shock absorbing member of the present embodiment was subjected to impact test.
[0085]
　In this study, we analyzed simulating the falling weight type impact test. Specifically, the shock absorbing member of the shape shown in FIG. 2, in a state arranged along the axial direction in the vertical direction, by dropping the impact body mass 700kg from a height 13.8 m, the shock absorbing member It was to collide with the one end. At that time, it calculates the load and the axial direction of the shaft direction of the collision object displacement to determine the relationship between load and displacement. Further, one for of the long side surfaces of the shock absorbing member after impact test to determine the displacement of the surface perpendicular direction (X direction) including the weld. Displacement in the X direction, on both sides of the intermediate plate, specifically, determined by P1 and P2 position of FIG. 2 (a).
[0086]
　Shock absorbing member 10, the axial length was 300 mm. Body 20, the cross-sectional shape was rectangular. A pair of long sides (20a, 20b) are all, W1 is 128mm, d1a is 56.6Mm, d1b was 83.4Mm, the distance between opposing long sides and 70 mm. Moreover, any edge line portion connecting the rectangular long side and short side has an arc of radius 6 mm. Middle plate 30, short side and a portion that is disposed parallel to the body 20 of which, provided so as to be positioned at the center of the opposite short sides. Body 20 and the intermediate plate 30 are both tensile strength with 980MPa grade steel.
[0087]
　Weld between the body 20 and the intermediate plate 30 sets the boundary conditions simulating the spot welding, more specifically, setting the boundary conditions to simulate a case of performing spot welding having a diameter of 5mm by 45mm pitch .
[0088]
　In the present invention example was the thickness of the body 20 0.8 mm, the thickness of the middle plate 30 and 2 mm. In Comparative Example 1 was the thickness of the body 20 0.8 mm, the thickness of the middle plate 30 and 1 mm. In Comparative Example 2, without providing the intermediate plate 30, the plate thickness of the main body 20 it was set to 0.8 mm.
[0089]
　Figure 6 is a diagram showing the relationship between the load of Examples and displacement (axial displacement). 6 shows a load (kN) at a load per unit mass (kN / kg). As shown in FIG. 6, when deformed initial displacement is less than about 10 mm, although the load in the present invention examples and comparative examples are comparable, if the displacement is more than 10 mm, a load of the present invention examples, comparison high in most than examples 1 and 2. That is, the shock absorbing member of the present embodiment is revealed to be excellent in energy absorption efficiency.
[0090]
　Figure 7 is a diagram showing a displacement in the X direction in the long side surface of the shock absorbing member in Comparative Example 1 and Comparative Example 2. From FIG. 7, in Comparative Example 1, the waveform due to the displacement was the same phase on both sides of the intermediate plate. In Comparative Example 1, and Comparative Example 2 without the intermediate plate, the wavelength becomes comparable.
[0091]
　Figure 8 is a diagram showing a displacement in the X direction in the long side surface of the shock absorbing member of the present invention Example 1 and Comparative Example 2. From FIG. 8, in the present invention embodiment, a portion of the waveform due to displacement, becomes opposite phase on both sides of the intermediate plate. Further, if provided with no intermediate plate compared with (Comparative Example 2 of FIG. 8), the wavelength is shortened the amplitude decreases.
[0092]
　Thus, the shock absorbing member of the present embodiment, buckling deformation with different phases occurs on both sides of the intermediate plate, the wavelength becomes shorter with the amplitude of the variations is reduced. Thus, the shock absorbing member of the present embodiment, it was confirmed that the energy absorption efficiency is excellent.
Industrial Applicability
[0093]
　The impact-absorbing member of the invention can be lightweight while ensuring absorption energy. Therefore, when applied to the crash box or frame member of an automobile, it can contribute greatly to improvement in fuel consumption.
DESCRIPTION OF SYMBOLS
[0094]
　1a, 1b crash box
　2 front side member
　3 the rear side member
　4, 4 'floor cross member
　5 bumper reinforcement
　6 center pillar
　7 side sill
　10 impact absorbing member
　10a welding position
　20 body
　20a first long side
　20b second long side
　21 first of the metal plate
　22 second metal plate
　30 intermediate plate

The scope of the claims
[Claim 1]
　There shock absorbing member for absorbing an impact load applied in the axial direction,
　said impact absorbing member is
　formed of a metal plate, and the body shape in the axial direction perpendicular cross-section is polygonal,
　a metal plate is configured, the intermediate plate provided along the axial direction in the hollow portion in the body
includes a
　said polygonal shape of the body has a pair of long sides facing each other,
　said intermediate plate, said body the polygonal shape are joined to each long side of the
　shock absorbing member thickness in said plate and wherein the thicker than the plate thickness of the body.
[Claim 2]
　Shock absorbing member according to claim 1, wherein the thickness of said body is 2.3mm or less.
[Claim 3]
　Shock absorbing member according to claim 1 or 2 thickness t1 (mm) of the main body, the thickness of the insertion plate t2 (mm) is characterized by satisfying the following formula (1).
　　1.3 × t1 ≦ t2 ··· (1 )
[Claim 4]
　It said pair of long sides are both impact absorbing member according to any one of claims 1 to 3, wherein the long side of the width W1 of (mm) is characterized by satisfying the following expression (2).
　　W1 / t1 ≧ 20 ··· (2 )
[Claim 5]
　The body is made of one metal plate,
　the mid plate, the joined by welding superimposed on each long side of the polygonal shape of the body,
　the pair of long sides are both width in said plate distance along the thickness center in said plate in the direction of the center position in the width direction of the long side up to the end points of the long side d1a (mm) and d1b
that (mm) satisfies the following formula (3) shock absorbing member according to any one of claims 1 to 4, wherein.
　　0.5 ≦ d1a / d1b ≦ 2 ··· (3)
[Claim 6]
　The body includes a first metal plate comprising a portion of the polygonal shape and is composed of a second metal plate formed with the remainder of the polygonal shape,
　the first metal plate and the second metal plate the joined by welding overlapped with said intermediate plate at each long side of the polygonal shape,
　the pair of long sides are both from said thickness center in said plate in the widthwise central position in said plate first distance along the width direction of the long side to the end point of the long sides of the first metal plate d3a (mm), and, the thickness center from the second in said plate in the widthwise central position in said plate distance along the width direction of the long side to the end point of the long sides of the metal plate d3b (mm) is as claimed in any one of claims 1 to 5, characterized by satisfying the following equation (4) shock absorbing member.
　　0.5 ≦ (d3a / t1a) / (d3b / t1b) ≦ 2 ··· (4)
　However, t1a (mm) is the thickness of the first metal plate, t1b (mm) is the second metal plate the plate is the thickness.
[Claim 7]
　Metal plate, tensile any one of the shock-absorbing member according to claim 1 to 6, wherein the strength 780MPa is more steel plates constituting the body.
[8.]
　Any one of the shock absorbing member according to claim 1 to 7, the Young's modulus of the metal plate constituting the intermediate plate is characterized in that at least 180 GPa.
[Claim 9]
　Automotive class shoe box, or a front side member, the rear side member, the side sill or the floor any one of the shock-absorbing member according to claim 1 to 8, characterized in that the cross member.