Shock absorbing material

Abstract

To provide a lightweight and inexpensive shock-absorbing material while maintaining shock absorption performance. [Solution] The shock-absorbing member 40 is formed by joining one end (hanging wall 23) of one S-shaped plate (second S-shaped plate 20B) to the upper part of the crank portion (wall portion 21) of another S-shaped plate (first S-shaped plate 20A), and joining the lower part of the crank portion (wall portion 21) of the first S-shaped plate (second S-shaped plate 20B) to the other end (upright wall 25) of the other S-shaped plate (first S-shaped plate 20A), thereby forming a cylindrical body 37 between the two S-shaped plates (between the first S-shaped plate 20A and the second S-shaped plate 20B). Two adjacent cylindrical bodies 37 share one S-shaped plate (second S-shaped plate 20B), and a number of S-shaped plates 20 are arranged along the longitudinal axis while the cylindrical bodies 37 extend along the cross axis.

Description

Technical Field

[0001] The present invention relates to a shock absorption member provided on the side portion of a vehicle body in preparation for a side collision.

[0002] [Explanation of Terms] · Side sill: A member corresponding to the threshold of the front and rear doors. · Longitudinal axis: A horizontal axis extending in the front-rear direction of the vehicle body. · Cross axis: A horizontal axis extending in the vehicle width direction. · Relatively move: Moving another member with respect to a certain member as a reference, or moving a certain member with respect to another member as a reference. · Three-point bending: The beam is supported at two points and a load is applied at one point, causing the beam to bend.

Background Art

[0003] It is desirable to provide a shock absorption member on the side portion of a vehicle body in preparation for a side collision. Various structures have been proposed as the shock absorption member (for example, see Patent Document 1 (FIG. 2)).

[0004] Patent Document 1 will be described based on the following figures. FIG. 15 is a perspective view of a conventional shock absorption member. As shown in FIG. 15, a conventional shock absorption member 100 includes a corrugated lower panel 101 bent up and down, a corrugated upper panel 102 bent up and down, and an external case 103 having a substantially U-shaped cross section for housing them.

[0005] In the figure, at the portion indicated by A, a part of the external case 103 overlaps the upper panel 102. Similarly, a part of the external case 103 overlaps the lower panel 101. Due to these weights, the weight of the shock absorption member 100 increases.

[0006] With the demand for weight reduction of the vehicle body, the increase in the weight of the shock absorption member 100 is not preferable. Therefore, shock-absorbing members with a structure that does not require an external case 103 have been proposed (see, for example, Patent Document 2 (Claim 4, Figure 4)). Patent Document 2 discloses a reinforcing member made from an extruded 6000 series or 7000 series aluminum alloy. Although it is explained that the reinforcing member may be made of steel, for example, this document will focus on a reinforcing member made from an extruded aluminum alloy.

[0007] Aluminum alloys have the advantage of being less dense than steel, but they have the disadvantage of being expensive. In addition, aluminum alloy reinforcing members have the disadvantage of corroding within steel side sills.

[0008] In other words, the impact-absorbing member disclosed in Patent Document 1 has the disadvantage of being heavy, and the impact-absorbing member disclosed in Patent Document 2 has the disadvantage of being expensive. In recent years, there has been a strong demand for lighter and more cost-effective vehicle bodies. Therefore, there is a need for lightweight and inexpensive shock-absorbing materials that maintain shock absorption performance. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] U.S. Patent No. 10370040 [Patent Document 2] Patent No. 7181799 [Overview of the project] [Problems that the invention aims to solve]

[0010] The present invention aims to provide a lightweight and inexpensive shock-absorbing member while maintaining shock-absorbing performance. [Means for solving the problem]

[0011] The present invention relates to a steel plate impact absorbing member provided on the side of a vehicle body in preparation for a side collision, When the horizontal axis extending from the front to the rear of the vehicle body is called the longitudinal axis, and the horizontal axis extending in the width direction of the vehicle body is called the cross axis, The vehicle body has at least two cross members extending parallel to the cross axis, and side sills that extend along the longitudinal axis and house the shock-absorbing members. The length of the impact-absorbing member along its longitudinal axis is set to be equal to or greater than the distance between the two cross members. The shock-absorbing member has a plurality of S-shaped plates, each S-shaped plate comprising a wall portion as a crank section, an upper surface portion extending horizontally from the upper end of the wall section, a hanging wall extending downward from the tip of the upper surface portion, a lower surface portion extending horizontally from the lower end of the wall section, and an upright wall extending upward from the tip of the lower surface portion, with one end of one S-shaped plate being joined to the upper part of the crank section of another S-shaped plate, and the lower part of the crank section of the one S-shaped plate being joined to the other end of the other S-shaped plate, thereby forming a cylindrical body between the two S-shaped plates, with two adjacent cylindrical bodies sharing the one S-shaped plate, and a strip-shaped structure in which a plurality of S-shaped plates are arranged along the longitudinal axis and the cylindrical bodies extend along the cross axis. [Effects of the Invention]

[0012] In this invention, a strip-shaped structure is formed by two adjacent cylindrical bodies sharing a single S-shaped plate material. In this strip-shaped structure, the cylindrical bodies distribute the load along the cross axis to the adjacent cylindrical bodies, thereby increasing the crush strength, i.e., the axial crush strength. When the aforementioned strip-shaped structure collides with a pole, it is supported by two cross members and bent by three-point bending. However, due to the high crush strength along the cross axis, local crushing is limited and the length of the cross axis is maintained. As a result, the strip-shaped structure is bent into a V-shape with the two cross members as fulcrums. At this time, the strip-shaped structure withstands compression on the pole side (hereinafter referred to as the outer side) and tension on the non-pole side (hereinafter referred to as the inner side), increasing the bending load and consequently increasing the amount of impact energy absorbed. Therefore, the impact-absorbing member of the present invention has a sufficiently large amount of impact energy absorption capacity.

[0013] In addition, since the S-shaped plate material is made of a relatively thin steel plate, it is lightweight. Furthermore, compared with an aluminum alloy, the steel plate (carbon steel plate) is significantly less expensive. The S-shaped plate material can be easily manufactured and mass-produced by roll-forming or press-forming a blank material. Furthermore, since two adjacent cylindrical bodies share one S-shaped plate material, the two cylindrical bodies are joined and continuous. As a result, the side impact load is dispersed in the longitudinal axis direction, so the axial crushing strength increases. Therefore, according to the present invention, there is provided a lightweight and inexpensive impact-absorbing member while maintaining the impact-absorbing performance.

Brief Description of the Drawings

[0014] [Figure 1] (a) and (b) are diagrams for explaining a method of manufacturing an S-shaped plate material according to the present invention. [Figure 2] (a) and (b) are diagrams for explaining a method of manufacturing a strip-shaped structure and impact-absorbing member, and (c) is a view taken in the direction of arrow c of (b). [Figure 3] (a) and (b) are diagrams for explaining a support structure of an impact-absorbing member. [Figure 4] (a) and (b) are diagrams for explaining a pole collision. [Figure 5] It is a graph for explaining impact energy absorption performance. [Figure 6] (a) to (c) are diagrams for explaining a method of manufacturing an outer protective member. [Figure 7] (a) to (c) are diagrams for explaining a method of manufacturing an impact-absorbing member. [Figure 8] It is a diagram for explaining a modified example of a support structure of an impact-absorbing member. [Figure 9] (a) to (c) are diagrams for explaining a further modified example of a support structure of an impact-absorbing member. [Figure 10] (a) to (c) are diagrams for explaining another pole collision. [Figure 11] (a) and (b) are diagrams for explaining positioning holes. [Figure 12](a) and (b) are diagrams illustrating different forms of the inner protective member. [Figure 13] This is a flowchart illustrating the method for manufacturing an impact-absorbing member according to the present invention. [Figure 14] Figures (a) to (c) are diagrams for comparing and examining the impact energy absorption performance. [Figure 15] This is a perspective view of a conventional shock-absorbing component. [Modes for carrying out the invention]

[0015] Embodiments of the present invention will be described below with reference to the attached drawings. [Examples]

[0016] As shown in Figure 1(a), a blank material 11 made of steel plate is prepared. This blank material 11 is preferably made of high-tensile steel with a tensile strength exceeding 900 MPa. This blank material 11 is subjected to roll forming or press forming.

[0017] [Roll forming] Roll forming is a forming method in which a blank material 11 is plastically deformed using, for example, an upper grooved roll and a lower grooved roll. To prevent cracks or fissures from forming in the strip-shaped blank material 11, it is desirable to gradually plastically deform it using multiple pairs of upper and lower rolls. By cutting it to a predetermined length, an S-shaped plate material 20 is obtained, which has a shape like an S rotated 90° clockwise, as shown in Figure 1(b). Note that the S-shaped plate material 20 is an S-shaped cross-section plate material.

[0018] [Press forming] Press forming is a molding method in which a blank material 11 is plastically deformed using, for example, an upper die (corresponding to a punch) having a convex portion and a lower die (corresponding to a die) having a concave portion. To prevent cracks or fissures from forming in the blank material 11, it is desirable to gradually plastically deform it using multiple pairs of upper and lower dies. As a result, an S-shaped plate material 20 is obtained, which has a shape like an S rotated 90° clockwise, as shown in Figure 1(b).

[0019] [High tensile strength steel] As ordinary steel, carbon steel with a tensile strength of 400 MPa is widely used. In contrast, if high-tensile steel of 900 MPa is used, the tensile strength is twice that of ordinary steel, so the plate thickness can be halved, and the weight of the S-shaped plate material 20 can be halved. Furthermore, as will be described later, it is possible to make the deformation primarily V-shaped, with crushing being secondary.

[0020] [S-shaped plate material] As shown in Figure 1(b), the S-shaped plate material 20 consists of a wall portion 21 as a crank section, an upper surface portion 22 extending horizontally from the upper end of the wall portion 21, a hanging wall 23 extending downward from the tip of the upper surface portion 22, a lower surface portion 24 extending horizontally from the lower end of the wall portion 21, and an upright wall 25 extending upward from the tip of the lower surface portion 24.

[0021] At this point, the boundary between the wall portion 21 and the upper surface portion 22 is made into a curved surface 26, also known as a rounded surface. While it is possible to make the boundary between the wall portion 21 and the upper surface portion 22 at a right angle, a curved surface 26 is easier to form than a right angle. Furthermore, a right angle concentrates stress, while a curved surface 26 has the advantage of not concentrating stress. Similarly, the boundary between the upper surface 22 and the hanging wall 23, the boundary between the wall 21 and the lower surface 24, and the boundary between the lower surface 24 and the upright wall 25 are made into curved surfaces 26.

[0022] While not mandatory, preferably, the upper surface 22 is provided with a downwardly convex protrusion 27, and the lower surface 24 is provided with an upwardly convex protrusion 27. Compared to the case without the protrusion 27, the presence of the protrusion 27 increases the length (left-right length in the drawing) of the upper surface 22 and the lower surface 24, increasing the range of bending deformation, as well as increasing rigidity and improving the impact energy absorption performance.

[0023] [Strip-shaped structure] Next, the manufacturing method of the strip-shaped structure 35 will be explained based on Figures 2(a) and (b). For convenience, one S-shaped plate 20 will be read as the first S-shaped plate 20A (the letters are subscripts to distinguish the first to third), and the other S-shaped plates 20 will be read as the second S-shaped plate 20B and the third S-shaped plate 20C.

[0024] As shown in Figure 2(a), a first S-shaped board 20A, a second S-shaped board 20B, and a third S-shaped board 20C are prepared, all of the same shape as the S-shaped board 20. Then, the first S-shaped plate 20A, the second S-shaped plate 20B, and the third S-shaped plate 20C are positioned such that one end of the first S-shaped plate faces the crank portion of the other S-shaped plate, and the crank portion of the first S-shaped plate faces the other end of the other S-shaped plate. Relatively, the second S-shaped plate 20B is placed against the first S-shaped plate 20A, and the first portion 28 in the figure is welded from above with the laser device 29. Next, the second portion 31 in the figure is welded from below with the laser device 29. Next, the second portion 31 in the figure is welded with the laser device 29. A weld bead 36 is formed by the welding. Alternatively, the lower laser device 29 may be omitted, and the S-shaped plate side may be reversed and welded with the upper laser device 29.

[0025] Next, the third S-shaped plate 20C is placed against the second S-shaped plate 20B, and the third portion 32 in the figure is welded using the laser device 29. Then, the fourth portion 33 in the figure is welded using the laser device 29. Furthermore, it is permissible to use two laser devices 29 to weld the first part 28 and the second part 31 together, and to weld the third part 32 and the fourth part 33 together, thereby shortening the welding time. By applying the above manufacturing method, multiple S-shaped plates 20 can be connected in such a manner as connecting the 4th S-shaped plate to the 3rd S-shaped plate 20C, and connecting the 5th S-shaped plate to the 4th S-shaped plate.

[0026] As a result, the strip-shaped structure 35 shown in Figure 2(b) is obtained. The strip-shaped structure 35 (which in this example also serves as an impact-absorbing member 40) is a structure in which one end (hanging wall 23) of one S-shaped plate (second S-shaped plate 20B) is joined to the upper part of the crank section (wall section 21) of another S-shaped plate (first S-shaped plate 20A), and the lower part of the crank section (wall section 21) of the first S-shaped plate (second S-shaped plate 20B) is joined to the other end (upright wall 25) of the other S-shaped plate (first S-shaped plate 20A). A cylindrical body 37 is formed between two S-shaped plates (between the first S-shaped plate 20A and the second S-shaped plate 20B). Next, a second cylindrical body 37 is formed from the second S-shaped plate 20B and the third S-shaped plate 20C, and these two cylindrical bodies 37 share one second S-shaped plate 20B. A number of S-shaped plates 20 are arranged along their longitudinal axes to obtain a rigidly connected strip-shaped structure 35.

[0027] The cylindrical body 37 is a rectangular tube. Furthermore, cylindrical body 37 and the adjacent cylindrical body 37 have the same internal cross-sectional area and the same length. Furthermore, as described above, since the boundary between the wall portion 21 and the upper surface portion 22 is made into a curved surface 26, a V-shaped groove portion 38 that opens outward is formed between one cylindrical body 37 and the adjacent cylindrical body 37.

[0028] The strip-shaped structure 35 can be described as a component in which multiple rectangular cylindrical bodies 37, 37, ... are arranged along their longitudinal axes and each is firmly connected to the others. As shown in Figure 2(c), the cylindrical bodies 37, 37, ... are long members that extend along the cross axis.

[0029] [Shock absorbing material] The strip-shaped structure 35 described above also serves as the shock-absorbing member 40. This shock-absorbing member 40 is housed in the side sill 50. It is also permissible to configure the shock-absorbing member 40 by attaching other members to the strip-shaped structure 35. Examples of modifications (alterations) with other members attached will be described later.

[0030] [Side sill] As shown in Figure 3(a), the side sill 50 is a hollow body extending along its longitudinal axis and consists of a side sill outer 51 having an upper flange 52 and a lower flange 53, and a side sill inner 54 having an upper flange 55 and a lower flange 56.

[0031] Furthermore, the impact-absorbing member 40 is arranged to extend along the cross axis, with the upper bracket 57 extending from approximately the central portion to the upper flange 52. Next, the upper bracket 57 is sandwiched between the upper flange 52 and the upper flange 55. Then, the side sill inner 54 is aligned with the side sill outer 51 and welded together. As a result, as shown in Figure 3(b), a configuration is obtained in which the shock-absorbing member 40 is housed in the side sill 50.

[0032] Furthermore, as shown in Figure 3(b), the impact absorbing member 40 is joined and fixed to the side sill 50 so that its height aligns with the cross member 61. Reference numeral 62 denotes the floor panel.

[0033] The upper bracket 57 may be replaced with the lower bracket 58 shown by the dashed line. That is, the lower bracket 58 extends from approximately the center of the impact absorbing member 40 to the lower flange 53. Next, the lower bracket 58 is fixed in place by sandwiching it between the lower flange 53 and the lower flange 56.

[0034] The function of the impact-absorbing member 40, which has the above configuration, will be explained based on Figures 4(a) and (b). For simplicity of explanation, the side sills 50 have been omitted. Also, the ends of the cross members have been rounded to illustrate the three-point bending. As shown in Figure 4(a), the impact-absorbing member 40 extending along the longitudinal axis is set to have a length greater than the distance between the two cross members 61. We assume that the pole 64 collides with such an impact-absorbing member 40. The impact-absorbing member 40 is supported at two points by the cross members 61, and a concentrated load is applied by the pole 64.

[0035] As a result, as shown in Figure 4(b), in a three-point bending configuration, the impact absorbing member 40 is bent into a V-shape with the two cross members 61, 61 as fulcrums. At this time, the cylindrical bodies 37, 37, ... extending along the cross axis share a single S-shaped plate material, connecting the two cylindrical bodies 37, 37 to each other and forming a continuous structure. Therefore, the lateral impact load is distributed in the longitudinal axis direction, resulting in high axial crush strength. The axial crush strength of the cross axis is high, and multiple cylindrical bodies 37 are integrated in the longitudinal axis direction. As a result, local crushing by the pole 64 and local crushing by the cross members 61 are limited, i.e., relatively minor. When crushing is minor, the length of the cylindrical body 37 along the cross axis (cylinder length) hardly changes. Consequently, crushing is secondary, and the V-shaped bending is dominant.

[0036] Due to the V-shaped bend, the outer portion of the impact-absorbing member 40 withstands compression, while the inner portion withstands tension. This increases the bending load. The correlation between this increase in bending load and the amount of impact energy absorbed is explained based on Figure 5.

[0037] Figure 5 is a graph illustrating the effects of the present invention, with the horizontal axis representing stroke and the vertical axis representing load. Conventionally, this type of impact absorbing member primarily relies on crushing, absorbing impact energy through crushing. With simple crushing, the load remains constant for strokes exceeding a certain level. In contrast, in the three-point bending method according to the present invention, the load increases in direct proportion to the stroke. As a result, compared to simple crushing, the present invention has the advantage of increasing the amount of impact energy absorbed by the amount indicated by the diagonal lines (\\\).

[0038] Furthermore, considering the collision of the pole 64 with the outside of the impact-absorbing member 40 and the collision of the impact-absorbing member 40 with the cross member 61 in Figures 4(a) and (b), it is desirable to protect the outside and inside of the impact-absorbing member 40 with some kind of material. Therefore, we propose an outer protective member 70 and an inner protective member 80 as protective components.

[0039] [Outer protection member] As shown in Figure 6(a), a blank material 11 is prepared. Preferably, this blank material 11 is made of high-tensile steel with a tensile strength exceeding 900 MPa. This blank material 11 is then roll-formed or press-formed.

[0040] As a result, the molded product 12 shown in Figure 6(b) is obtained. The edge 13 of the molded product 12 is cut by trimming. Then, by rotating it counterclockwise in the drawing, the outer protective member 70 shown in Figure 6(c) is obtained. The outer protective member 70 is a long material with a W-shaped cross-section similar to that of a typical guardrail.

[0041] As shown in Figure 6(c), the outer protective member 70 is composed of a corrugated sheet portion 71 extending vertically and an upper plate portion 72 and a lower plate portion 73 extending inward from both ends of the corrugated sheet portion 71. The corrugated sheet portion 71 has at least one wave portion 74 projecting to the left (inward). While not essential, preferably, the upper plate portion 72 is provided with an upper curl portion 75 that curves upward at its tip, and the lower plate portion 73 is provided with a lower curl portion 76 that curves downward at its tip.

[0042] [Internal protective material] The inner protective member 80 can be the same shape as the outer protective member 70. If they are the same shape, there is no need to prepare a roll or mold for forming the inner protective member 80, thus reducing manufacturing costs.

[0043] [Examples of changes to shock-absorbing materials] As shown in Figure 7(a), the strip-shaped structure 35 is inserted relative to the outer protective member 70. Since it is relative, the outer protective member 70 may also be fitted into the strip-shaped structure 35. At this time, the upper curl portion 75 and the lower curl portion 76 perform a centering function. That is, even if the height center of the strip-shaped structure 35 is offset to some extent from the height center of the outer protective member 70, the upper curl portion 75 and the lower curl portion 76 play a role in correcting the misalignment. As a result, one end of the cylindrical body 37 is smoothly inserted between the upper plate portion 72 and the lower plate portion 73.

[0044] Next, as shown in Figure 7(b), the upper plate portion 72 and the lower plate portion 73 are welded to one end of the cylindrical body 37. Then, the inner protective member 80 is fitted to the other end of the cylindrical body 37.

[0045] As shown in Figure 7(c), the inner protective member 80 is welded to the other end of the cylindrical body 37. Preferably, the outer protective member 70 is joined to one end of the cylindrical body 37 by a weld bead 36 extending along the cross axis. Furthermore, the inner protective member 80 is joined to the other end of the cylindrical body 37 by a weld bead 36 that extends along the front-to-back direction (longitudinal axis) of the drawing.

[0046] As described above, an impact absorbing member 40 is obtained, consisting of an outer protective member 70, a strip-shaped structure 35, and an inner protective member 80. However, it is also permissible to omit the inner protective member 80 and construct the impact absorbing member 40 with only the outer protective member 70 and the strip-shaped structure 35.

[0047] The impact-absorbing member 40, consisting of the above configuration, is housed in the side sill 50, as shown in Figure 8. Since the other components are the same as those in Figure 3(b), a detailed explanation is omitted, using the same reference numerals as in Figure 3(b).

[0048] The upper bracket 57 and lower bracket 58 shown in Figure 8 may be replaced with the bulkhead 82 described in Figure 9(a). As shown in Figure 9(b), the bulkhead 82 is welded to the side sill inner 54. The bulkhead 82 has a groove 83 that opens outward midway along its height. The shock-absorbing member 40 is inserted into this groove 83.

[0049] As shown in Figure 9(c), the shock-absorbing member 40 is housed in the side sill 50 while being supported by the bulkhead 82. It is acceptable to combine the upper bracket 57 with the bulkhead 82, or to combine the lower bracket 58 with the bulkhead 82.

[0050] The function of the shock-absorbing member 40 will be explained based on Figures 10(a) to (c). In Figure 10(a), the outer protective member 70 comes into contact with the pole 64. As a result, the outer protective member 70 begins to deform, and the wave portion 74 provided on the outer protective member 70 moves relatively closer to one end of the cylindrical body 37.

[0051] In Figure 10(b), the wave portion 74 acts as a wedge, causing one end of the cylindrical body 37 to undergo plastic deformation upwards and downwards. In Figure 10(c), the outer protective member 70 deforms, and one end of the cylindrical body 37 undergoes further plastic deformation upwards and downwards. At this time, the outer protective member 70 extends vertically to withstand a large compressive load. As a result, the outer protective member 70 adequately protects the cylindrical body 37.

[0052] Further modifications of the present invention are described below. Figure 11(a) is a plan view illustrating a modified example of the strip-shaped structure, and Figure 11(b) is a cross-sectional view thereof. As shown in Figure 11(b), it is desirable to drill positioning holes 85 in the upper surface 22 and the lower surface 24 of the strip-shaped structure 35. The positioning holes 85 may be drilled in only one of the upper surface 22 or the lower surface 24.

[0053] As shown in Figure 11(a), it is desirable that the positioning holes 85 be arranged in a staggered pattern along the longitudinal axis. However, the staggered arrangement includes two positioning holes 85 arranged along the cross axis.

[0054] The positioning hole 85 is useful in determining the position of the second S-shaped plate 20B relative to the first S-shaped plate 20A in Figure 2(a). For example, when shifting the second S-shaped plate 20B along the cross axis relative to the first S-shaped plate 20A, the shifting direction becomes linear because the two positioning holes 85 are aligned with the cross axis. In other words, the staggered positioning holes 85 allow for linear adjustment of the shift direction.

[0055] In addition, the positioning holes 85 act as weight-reducing holes, promoting weight reduction of the strip-shaped structure 35. Because they are arranged in a staggered pattern, the reduction in strength is small, and the reduction in strength can be kept to a minimum.

[0056] [Example of an inner protective component] The inner protective member 80 exhibiting a W-shaped cross-section as described in Figure 7(b) may be the inner protective member 80 with a U-shaped cross-section as shown in Figure 12(a). As shown in Figure 12(a), the inner protective member 80 consists of a wide plate portion 87 that is sufficiently taller than the cylindrical body 37, an upper plate portion 88 that extends horizontally from the upper end of the wide plate portion 87, and a lower plate portion 89 that extends horizontally from the lower end of the wide plate portion 87.

[0057] There is a sufficiently large space between the cylindrical body 37 and the upper plate portion 88, and there is a sufficiently large space between the cylindrical body 37 and the lower plate portion 89. These spaces allow for the insertion of laser devices (or welding guns), which has the advantage of facilitating welding operations.

[0058] As shown in Figure 12(b), the impact absorbing member 40 is housed in the side sill 50 by attaching the side sill outer 51 to the side sill inner 54.

[0059] The manufacturing method of the impact-absorbing member 40 described above will be explained with reference to Figure 13. The first molding process is carried out at step number 01 (hereinafter referred to as ST) in Figure 13.

[0060] In the first forming process, as shown in Figures 6(a) and (b), a blank material 11 made of steel plate is roll-formed or press-formed to produce an outer protective member 70 with a W-shaped cross-section, as shown in Figure 6(c), which consists of a corrugated sheet portion 71 extending vertically, an upper plate portion 72 and a lower plate portion 73 extending inward from both ends of the corrugated sheet portion 71, an upper curl portion 75 extending upward in a curved shape from the tip of the upper plate portion 72, and a lower curl portion 76 extending downward in a curved shape from the tip of the lower plate portion 73.

[0061] Next, the second molding process is carried out in ST02. This second molding process may be carried out in parallel with the first molding process, or before the first molding process.

[0062] In the second molding process, as shown in Figures 1(a) and (b), the blank material 11 is roll-formed or press-formed to produce multiple S-shaped plate materials 20, each having a wall portion 21 (crank portion), an upper surface portion 22 extending horizontally from the upper end of the wall portion 21 (crank portion), a hanging wall 23 extending downward from the tip of the upper surface portion 22, a lower surface portion 24 extending horizontally from the lower end of the wall portion 21 (crank portion) in the opposite direction to the upper surface portion 22, and an upright wall 25 extending upward from the tip of the lower surface portion 24.

[0063] Next, the first welding process is performed using ST03. In the first welding process, as shown in Figures 2(a) and (b), a weld bead 36 is formed along the entire length of the cylindrical body 37 by laser welding an S-shaped plate material 20 and an adjacent S-shaped plate material 20 together while moving them along the cross axis, and the strip-shaped structure 35 is manufactured by repeatedly joining an S-shaped plate material 20 to an adjacent S-shaped plate material 20 using the weld bead 36.

[0064] Next, the second welding process is performed using ST04. In the second welding process, as shown in Figure 7(a), the strip-shaped structure 35 is set on the outer protective member 70 by inserting it between the upper curl portion 75 and the lower curl portion 76. Then, as shown in Figure 7(b), the upper plate portion 72 is laser-welded to the upper surface portion 22, and the lower plate portion 73 is laser-welded to the lower surface portion 24, thereby manufacturing the impact absorbing member 40 shown in Figure 7(c).

[0065] The manufacturing method of the shock-absorbing member 40 described above provides the following effects. Roll forming or press forming offers high mass productivity, and since multiple S-shaped plate materials 20 are laser-welded while being offset, the strip-shaped structure 35 can be easily manufactured. Furthermore, when setting the strip-shaped structure 35 onto the outer protective member 70, it is drawn in by the upper curl portion 75 and the lower curl portion 76, making the setting work easier. In addition, a weld bead 36 is formed along the entire length of two cylindrical bodies 37, 37 that share a single S-shaped plate material by laser welding, and multiple such cylindrical bodies 37, 37, ... are welded together to form the strip-shaped structure 35, which generates large compression and tension in the three-point bending.

[0066] Based on the above description, the present invention can be summarized as follows. As shown in Figure 3(b), the impact absorbing member 40 made of steel plate is provided on the side of the vehicle body 60 in preparation for a side collision, When the horizontal axis extending from the front to the rear of the vehicle body 60 is called the longitudinal axis, and the horizontal axis extending in the width direction of the vehicle body 60 is called the cross axis, The vehicle body 60 has at least two cross members 61 extending parallel to the cross axis, and a side sill 50 that extends along the longitudinal axis and houses the shock absorbing member 40. As shown in Figure 4(a), the length of the shock-absorbing member 40 along its longitudinal axis is set to be equal to or greater than the distance between the two cross members 61. As shown in Figure 2(b), the shock-absorbing member 40 is a strip-shaped structure 35 in which a number of S-shaped plates 20 are arranged along the longitudinal axis, and the cylindrical body 37 extends along the cross axis as shown in Figure 2(c). This is achieved by joining one end (hanging wall 23) of one S-shaped plate 20 (second S-shaped plate 20B) to the upper part of the crank portion (wall portion 21) of another S-shaped plate 20 (first S-shaped plate 20A), and joining the lower part of the crank portion (wall portion 21) of the first S-shaped plate 20B to the other end (upright wall 25) of the other S-shaped plate 20 (first S-shaped plate 20A).

[0067] The effects of the impact-absorbing member 40, which has the above configuration, have been described in the section on [Effects of the Invention], so they will be omitted here.

[0068] Preferably, as shown in Figure 1(b), the S-shaped plate material 20 has at least a wall portion 21 corresponding to the crank portion, an upper surface portion 22 extending horizontally from the upper end of the wall portion 21, and a lower surface portion 24 extending horizontally from the lower end of the wall portion 21 in the opposite direction to the upper surface portion 22. The upper portion 22 has a protruding ridge 27 that is convex downward or upward, and the lower portion 24 has a protruding ridge 27 that is convex upward or upward.

[0069] The protruding portion 27 forms a groove that extends along the cross axis, increasing the crush strength and contributing to improved impact energy absorption performance during three-point bending.

[0070] Preferably, as shown in Figure 2(b), there is an outward-opening groove 38 between the cylindrical body 37 and the adjacent cylindrical body 37.

[0071] The groove 38 extends along the cross axis, increasing the crush strength and contributing to improved impact energy absorption performance during three-point bending.

[0072] Preferably, as shown in Figure 2(b), the cylindrical body 37 is a rectangular tube, and the cylindrical body 37 and the adjacent cylindrical body 37 have the same internal cross-sectional area and the same length.

[0073] The cylindrical body 37 extends along the cross axis, increasing the crush strength and contributing to improved impact energy absorption performance during three-point bending.

[0074] When referring to the side receiving the external force in a side collision as the outside, and the side opposite to this outside as the inside, Preferably, as shown in Figure 7(c), an outer protective member 70 having a W-shaped cross-section and extending along the longitudinal axis to protect the cylindrical body 37 is attached to the outside of the cylindrical body 37.

[0075] If the outer protective member 70 is a member with a simple U-shaped cross-section extending vertically, it will bend and deform relatively easily. In contrast, the outer protective member 70 according to the present invention is a member exhibiting a W-shaped cross-section, and is therefore resistant to bending deformation. As a result, large compressive loads and tensile loads can be generated during three-point bending. Specifically, the corrugated sheet portion 71 increases bending rigidity, and the force acting parallel to the plane on the upper plate portion 72 and the lower plate portion 73 further increases bending rigidity. Therefore, three-point bending deformation can be performed without localized breakage. As a result, as shown in Figure 5, the deformation load becomes larger than the conventional local crushing load, making it possible to increase the amount of impact energy absorbed for the same displacement (stroke).

[0076] Preferably, as shown in Figure 6(c), the W-shaped cross section of the outer protective member 70 is composed of a corrugated sheet portion 71 extending vertically and an upper plate portion 72 and a lower plate portion 73 extending inward from both ends of the corrugated sheet portion 71.

[0077] The outer protective member 70 does not undergo localized crushing, but instead receives a large compressive load during three-point bending deformation.

[0078] When referring to the side receiving the external force in a side collision as the outside, and the side opposite to this outside as the inside, Preferably, as shown in Figure 7(c), an inner protective member 80 having a W-shaped cross-section and extending along the longitudinal axis to protect the cylindrical body 37 is attached to the inside of the cylindrical body 37.

[0079] The inner protective member 80 does not undergo localized crushing, and instead increases the tensile load (tension) during three-point bending deformation.

[0080] When referring to the side receiving the external force in a side collision as the outside, and the side opposite to this outside as the inside, Preferably, as shown in Figure 12(b), an inner protective member 80 having a U-shaped cross-section and extending along the longitudinal axis to protect the cylindrical body 37 is attached to the inside of the cylindrical body 37.

[0081] By joining the inner protective member 80 to the side sill inner 54, the inner protective member 80 becomes integrated with the side sill inner 54, increasing the tensile load (tension) during three-point bending deformation.

[0082] Preferably, as shown in Figure 7(c), the outer protective member 70 is joined to the cylindrical body 37 by a weld bead 36 extending along the cross axis.

[0083] Because the weld bead 36 extends along the cross axis, the impact absorbing member can increase the compressive load on the outer side (impact side) during three-point bending deformation.

[0084] Preferably, as shown in Figure 7(c), the inner protective member 80 is joined to the cylindrical body 37 by a weld bead 36 extending along the longitudinal axis.

[0085] Because the weld bead 36 extends along the longitudinal axis, the impact absorbing member can increase the internal tensile load during three-point bending deformation.

[0086] Preferably, as shown in Figure 3(b), the side sill 50 consists of a side sill outer 51 having an upper flange 52 and a lower flange 53, and a side sill inner 54 having an upper flange 55 and a lower flange 56. The impact absorbing member 40 is supported by an upper bracket 57 that extends upward from the center of the impact absorbing member 40 along the cross axis and is sandwiched between a pair of upper flanges 52 and 55, or by a lower bracket 58 that extends downward from the center of the impact absorbing member 40 along the cross axis and is sandwiched between a pair of lower flanges 53 and 56.

[0087] Because it is supported by the upper bracket 57 (or lower bracket 58), the impact absorbing member 40 maintains a stable posture within the side sill 50.

[0088] Preferably, as shown in Figure 9(b), the side sill 50 has a bulkhead 82 fixed to the side sill inner 54, and this bulkhead 82 has a groove 83 that opens outward. As shown in Figure 9(c), the shock-absorbing member 40 is supported in a manner that it is inserted into the groove 83.

[0089] Because it is supported by the bulkhead 82, the impact absorbing member 40 maintains a stable position within the side sill 50.

[0090] Preferably, as shown in Figures 11(a) and (b), staggered positioning holes 85 are further formed in at least one of the upper surface portion 22 and the lower surface portion 24. The positioning hole 85 includes two positioning holes 85 arranged along the cross axis, The positioning holes 85 are used to position adjacent S-shaped plate materials 20 relative to the S-shaped plate material 20 during the first welding process.

[0091] The staggered positioning holes 85 allow for linear adjustment of the displacement direction.

[0092] The impact-absorbing member 40 of the present invention, as described above, also demonstrates superior performance in responding to pole collisions. The response performance will be explained below based on Figures 14(a) to (c). Figure 14(a) is an external view (comparative example) of the impact absorbing member 100 disclosed in Patent Document 1. Note that the external case is omitted in this figure. As shown in Figure 14(a), the impact absorbing member 100 consists of a lower panel 101 joined to an upper panel 102, a hexagonal cylindrical crushing can 104, and a web 105 connecting the crushing can 104 to the adjacent crushing can 104.

[0093] We will examine the case where pole 107A collides with the crushed can 104 from the front of the drawing, and the case where pole 107B collides with the web 105. Figure 14(c) is a diagram illustrating the buckling load of a typical column. As is well known, if the length of the column is L, the Young's modulus of the column is E, the second moment of area of ​​the column is I, and the buckling load applied to the column is Pk, then structurally, Pk = (π 2 EI) / (4L 2 The equation ) holds true.

[0094] The second moment of area I at the crushed can 104 is proportional to the cube of the sum of the distance h1 from the center to the thickness center of the upper panel 102 and the distance h1 from the center to the thickness center of the lower panel 101 (h1 + h1).

[0095] The second moment of area I at the web 105 is proportional to the cube of the sum of the distance h2 from the center to the thickness center of the upper panel 102 and the distance h2 from the center to the thickness center of the lower panel 101 (h2 + h2).

[0096] Pk=(π 2 EI) / (4L 2 In this example, E and L are common to both the crushed can 104 and the web 105. If Pk1 is the buckling load at which the crushed can 104 begins to buckle, and Pk2 is the buckling load at which the web 105 begins to buckle, then the second moment of area I in the crushed can 104 is significantly larger than the second moment of area I in the web 105, so PK1 is significantly larger than PK2.

[0097] As a result, in Figure 14(a), the crushed can 104 is difficult to crush, while the web 105 is easily crushed. Thus, in the conventional impact-absorbing member 100 connected by a crushed can 104 and a web 105, the crushing load changes significantly when the so-called point of impact changes, resulting in a large difference in impact absorption energy. From the perspective of protecting the occupants, a structure is required that does not result in a difference in impact absorption energy even if the point of impact changes.

[0098] Therefore, we will examine the case in which the impact absorbing member 40 according to the present invention, as shown in Figure 14(b), collides relatively with the center of the cylindrical body 37, and the case in which the pole 64B collides with a position midway between the cylindrical body 37 and the adjacent cylindrical body 37.

[0099] The second moment of area I at the center of the cylindrical body 37 is proportional to the cube of the distance h3 between the upper surface 22 and the lower surface 24. The second moment of area I at the midpoint between the cylindrical body 37 and the adjacent cylindrical body 37 is the sum of the second moment of area I at the center of the cylindrical body 37 and the second moment of area I of the wall portion 21 itself.

[0100] Incidentally, taking an H-beam as an example, an H-beam consists of a web and a pair of upper and lower flanges, but the majority of the second moment of area I of the H-beam is generated in the flanges, and the contribution of the web is small. Since the web of the H-shaped steel and the wall portion 21 shown in Figure 14(b) are the same, the second moment of area I of the wall portion 21 is small. Therefore, there is no significant difference between the second moment of area I at the center of the cylindrical body 37 and the second moment of area I at a position midway between cylindrical body 37 and the adjacent cylindrical body 37.

[0101] As a result, the impact-absorbing member 40 according to the present invention has a structure that results in almost no difference in impact absorption energy even if the point of impact changes.

[0102] Furthermore, because the two cylindrical bodies are joined by sharing a single S-shaped plate, the bending deformation strength is increased, resulting in a V-shaped bending deformation between the two cross members during a pole collision. This creates compression on the outside and tension on the inside, allowing for greater impact energy absorption compared to the localized crushing in the comparative example.

[0103] In this embodiment, the S-shaped plate material 20 consists of a wall portion 21 as a crank section, an upper surface portion 22 extending horizontally from the upper end of the wall portion 21, a hanging wall 23 extending downward from the tip of the upper surface portion 22, a lower surface portion 24 extending horizontally from the lower end of the wall portion 21, and an upright wall 25 extending upward from the tip of the lower surface portion 24. However, the hanging wall 23 and the upright wall 25 should be shortened or eliminated to reduce weight. In this case, the strip-shaped structure is formed in which the end of the upper surface portion of one S-shaped plate material is joined to the upper end of the crank section (wall portion 21) of another S-shaped plate material, and the lower end of the crank section (wall portion 21) of one S-shaped plate material is joined to the end of the lower surface portion of another S-shaped plate material. The number and direction of the weld beads 36 between the outer protective member 70, the inner protective member 80, and the cylindrical body 37 may be changed according to the three-point bending characteristics. [Industrial applicability]

[0104] This invention is suitable for impact-absorbing members provided on the side of a vehicle body in preparation for side collisions. [Explanation of Symbols]

[0105] 11...Blank material, 20...S-shaped plate material, 21...Wall section, 22...Top section, 23...Draper wall, 24...Bottom section, 25...Upright wall, 27...Protruding section, 29...Laser device, 35...Strip-shaped structure, 36...Weld bead, 37...Cylindrical body, 38...Groove section, 40...Impact absorbing member, 50...Side sill, 51...Side sill outer, 52...Upper flange, 53...Lower flange, 54...Side sill inner, 55...Upper flange, 56...Lower flange, 57...Upper bracket, 58...Lower bracket, 60...Body, 61...Cross member, 70...Outer protective member, 71...Corrugated sheet section, 72...Upper plate section, 73...Lower plate section, 74...Corrugated section, 75...Upper curled section, 76...Lower curled section, 80...Inner protective member, 82...Bulkhead, 83...Groove, 85...Positioning hole.

Claims

1. A steel plate impact-absorbing member provided on the side of the vehicle body in preparation for a side collision, When the horizontal axis extending from the front to the rear of the vehicle body is called the longitudinal axis, and the horizontal axis extending in the width direction of the vehicle body is called the cross axis, The vehicle body has at least two cross members extending parallel to the cross axis, and side sills that extend along the longitudinal axis and house the shock-absorbing members. The length of the impact-absorbing member along its longitudinal axis is set to be equal to or greater than the distance between the two cross members. The impact absorbing member is characterized by having a plurality of S-shaped plates, each S-shaped plate comprising a wall portion as a crank section, an upper surface portion extending horizontally from the upper end of the wall section, a hanging wall extending downward from the tip of the upper surface portion, a lower surface portion extending horizontally from the lower end of the wall section, and an upright wall extending upward from the tip of the lower surface portion, with one end of one S-shaped plate being joined to the upper part of the crank section of another S-shaped plate, and the lower part of the crank section of the one S-shaped plate being joined to the other end of the other S-shaped plate, thereby forming a cylindrical body between the two S-shaped plates, with two adjacent cylindrical bodies sharing the one S-shaped plate, and a strip-shaped structure in which a plurality of S-shaped plates are arranged along the longitudinal axis and the cylindrical bodies extend along the cross axis.

2. The shock-absorbing member according to claim 1, The impact absorbing member is characterized in that the upper portion has a protruding ridge that is convex downward or upward, and the lower portion has a protruding ridge that is convex upward or upward.

3. The shock-absorbing member according to claim 2, An impact-absorbing member characterized by having an outward-opening groove between the aforementioned cylindrical body and an adjacent cylindrical body.

4. The shock-absorbing member according to claim 1, The shock-absorbing member is characterized in that the cylindrical body is a rectangular tube, and the cylindrical body and the adjacent cylindrical body have the same internal cross-sectional area and the same cylindrical length.

5. The shock-absorbing member according to claim 1, When referring to the side receiving the external force in a side collision as the outside, and the side opposite to this outside as the inside, An impact-absorbing member characterized in that an outer protective member having a W-shaped cross-section and extending along the longitudinal axis to protect the cylindrical body is attached to the outer side of the cylindrical body.

6. The shock-absorbing member according to claim 5, The impact absorbing member is characterized in that the W-shaped cross-section of the outer protective member is composed of a corrugated sheet portion extending vertically and an upper plate portion and a lower plate portion extending inward from both ends of the corrugated sheet portion.

7. The shock-absorbing member according to claim 1, When referring to the side receiving the external force in a side collision as the outside, and the side opposite to this outside as the inside, An impact-absorbing member characterized in that an inner protective member having a W-shaped cross-section and extending along the longitudinal axis to protect the cylindrical body is attached to the inside of the cylindrical body.

8. The shock-absorbing member according to claim 1, When referring to the side receiving the external force in a side collision as the outside, and the side opposite to this outside as the inside, An impact-absorbing member characterized in that an inner protective member having a U-shaped cross-section and extending along the longitudinal axis to protect the cylindrical body is attached to the inside of the cylindrical body.

9. The shock-absorbing member according to claim 5, The impact absorbing member is characterized in that the outer protective member is joined to the cylindrical body by a weld bead extending along the cross axis.

10. The shock-absorbing member according to claim 7, The impact absorbing member is characterized in that the inner protective member is joined to the cylindrical body by a weld bead extending along the longitudinal axis.

11. The shock-absorbing member according to claim 1, The side sill consists of a side sill outer having an upper flange and a lower flange, and a side sill inner having an upper flange and a lower flange. An impact absorbing member characterized in that the impact absorbing member is supported by an upper bracket extending upward from the center of the impact absorbing member along the cross axis and sandwiched by a pair of upper flanges, or by a lower bracket extending downward from the center of the impact absorbing member along the cross axis and sandwiched by a pair of lower flanges.

12. The shock-absorbing member according to claim 1, When referring to the side receiving the external force during a side collision as the outside, The side sill has a bulkhead fixed to the side sill inner, and this bulkhead has a groove that opens outward. The shock-absorbing member is characterized in that it is supported in a manner that it is inserted into the groove.

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