JP7604545B2 - Shock absorbing member, manufacturing method of shock absorbing member for automobile and manufacturing method of side sill - Google Patents

Description

The present invention relates to a shock absorbing member that absorbs shock applied to the side of an automobile body, a manufacturing method for an automobile shock absorbing member, and a manufacturing method for a side sill.

Conventionally, a reinforcing member for reinforcing the side of an automobile body is described, for example, in Patent Document 1. The reinforcing member disclosed in this publication is provided inside the side sill of the vehicle body, and has multiple hollow sections that have a closed cross-sectional shape when viewed from the front-to-rear direction of the vehicle body. The multiple hollow sections are formed by extrusion molding using an aluminum alloy as the material, and extend in the front-to-rear direction of the vehicle body while being aligned in a row in the vehicle width direction. This reinforcing member absorbs impacts applied to the side of the vehicle body toward the inside of the vehicle body by collapsing the hollow sections.

JP 2018-90021 A

The reinforcing member described in Patent Document 1 had the problem of high manufacturing costs because aluminum alloys are more expensive than steel plates and the equipment required for extrusion molding is expensive.

The objective of the present invention is to produce inexpensive impact absorbing components made of steel plates with good productivity.

In order to achieve this object, the manufacturing method of an automobile shock absorbing member according to the present invention includes a closed cross section half forming step of press-forming a steel plate blank into a hat-shaped cross section having a top of a hat portion , a pair of inclined walls, a pair of grooves including the inclined walls, and a brim to form a closed cross section half; and a closed cross section half forming step of combining at least three or more of the closed cross section half portions in an orientation in which the convex directions of the hat portions are opposite to each other, overlapping and joining the top of the hat portion of one of the closed cross section half portions and the brim portion of the other closed cross section half portion so as to extend in the longitudinal direction , to form a plurality of closed cross section constituents consisting of upper and lower grooves including the inclined walls of the hat portion, and connected only in the longitudinal direction by a connecting piece formed by overlapping the brim portion and the top. The closed cross section constituents are hollow bodies perpendicular to the longitudinal direction, have the connecting piece between adjacent hollow bodies, and are arranged in a plurality in the longitudinal direction, the hollow bodies form a closed cross section by the upper and lower grooves, and the upper and lower sides of the closed cross section each have at least two or more corner edges perpendicular to the longitudinal direction.

In addition, in the present invention, the groove may be provided with one or more of the following: a step shape, a smaller groove, two or more smaller second grooves, a protrusion, and a V-shaped recess in cross section.

The present invention may further comprise fixing members protruding outward from the inclined walls of the hat portions of the opposed closed cross-section half portions of the impact absorbing member.

The present invention may also include a step of joining the impact absorbing member formed by the impact absorbing member manufacturing method to a side sill outer, and a step of joining the side sill outer to which the impact absorbing member is joined and the side sill inner.

The present invention may also include a step of joining the impact absorbing member formed by the impact absorbing member manufacturing method to a side sill inner, and a step of joining the side sill inner to which the impact absorbing member is joined and the side sill outer.

The impact absorbing member of the present invention is formed by combining at least three or more closed cross section half portions having a hat-shaped cross section, the hat portion having a top , a pair of inclined walls, a pair of grooves including the inclined walls, and a brim, in an orientation in which the convex directions of the hat portion are opposite to each other, and overlapping and joining the top of the hat portion of one of the closed cross section half portions with the brim portion of the other closed cross section half portion so as to extend in the longitudinal direction, to form an impact absorbing member that consists of upper and lower grooves including the inclined walls of the hat portion and forms a plurality of closed cross section constituents connected only in the longitudinal direction by a connecting piece formed by overlapping the brim portions and the tops, the closed cross section constituents being hollow bodies perpendicular to the longitudinal direction, having the connecting pieces between adjacent hollow bodies, and being arranged in plurality in the longitudinal direction, the hollow bodies forming a closed cross section by the upper and lower grooves, and the upper and lower sides of the closed cross section each having at least two or more angular edges perpendicular to the longitudinal direction .

According to the present invention, at least two sets of steel plates are made in which half of the hollow body ( the inclined wall/groove of the hat portion) and the connecting piece ( the top and brim portion of the hat portion ) are formed by bending and pressing, and these steel plates are combined to form an impact absorbing member including a hollow body .
Therefore, the shock absorbing member can be manufactured by simply bending and pressing a steel plate, which is cheaper than an aluminum alloy, and welding (or riveting or other fastening means). Therefore, it is possible to provide a cheap shock absorbing member made of a steel plate.

In particular, if there is one die for press-molding one cap part , groove and brim, it is possible to inexpensively obtain an impact absorbing member of any length by connecting multiple hollow bodies in the longitudinal direction like stepping stones via connecting pieces . By simply adding a groove between the top and brim , the number of corner edges of the hollow body can be increased, thereby increasing the amount of impact energy absorbed. This is because the corner edges of this hollow body absorb impact energy by buckling sequentially from the tip to the base end when a load is applied from the side.

In addition, according to the present invention, the shock absorbing member can be attached to the side sill outer with a fixing member, and the side sill outer can be attached to the side sill inner in an integrated state, so that automobile side sills can be manufactured with high productivity using the shock absorbing member formed from steel plate.

FIG. 1 is a perspective view of a portion of an automobile body frame, showing an exploded side sill. FIG. 2 is a cross-sectional view of a side sill. FIG. 3 is a perspective view of the impact absorbing member and a front view thereof seen from the vehicle body side. FIG. 4 is a perspective view of a closed cross-sectional half and a cross-sectional view of a closed cross-sectional body. FIG. 5 is a perspective view of a closed cross-sectional half having a sill outer fixing member. FIG. 6 is a front view of a portion of the impact absorbing member showing an example of the formation of the sill outer fixing member. FIG. 7 is a flow chart for explaining an example of a method for manufacturing the impact absorbing member. FIG. 8 is a front view for explaining an example of a manufacturing method for the impact absorbing member. FIG. 9 is a flow chart for explaining an example of a method for manufacturing the impact absorbing member. FIG. 10 is a perspective view for explaining an example of a manufacturing method for the impact absorbing member. FIG. 11 is a flow chart for explaining an example of a method for manufacturing the impact absorbing member. FIG. 12 is a perspective view for explaining an example of a manufacturing method for the impact absorbing member. FIG. 13 is a flowchart for explaining an example of a method for manufacturing the impact absorbing member. FIG. 14 is a front view for explaining an example of a manufacturing method for the impact absorbing member. FIG. 15 is a flowchart illustrating an example of a method for manufacturing a side sill. FIG. 16 is a cross-sectional view for explaining an example of a manufacturing method for a side sill. FIG. 17 is a flowchart for explaining a modified example of the method for manufacturing a side sill. FIG. 18 is a schematic diagram for explaining the configuration of the impact absorbing member. FIG. 19 is a schematic diagram for explaining the configuration of the side sill. FIG. 20 is a cross-sectional view for explaining the shock absorbing principle of the shock absorbing member. FIG. 21 is a cross-sectional view for explaining the shock absorbing principle of the shock absorbing member. FIG. 22 is a perspective view showing another embodiment of the closed cross-sectional half portion. FIG. 23 is a perspective view showing another embodiment of the impact absorbing member. FIG. 24 is a cross-sectional view showing a modified example of a closed cross-section having a corner.

(First embodiment)
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a shock absorbing member, a manufacturing method for a shock absorbing member, and a manufacturing method for a side sill according to the present invention will be described in detail below with reference to FIGS.
The vehicle body frame 1 shown in Fig. 1 can be used for an electric vehicle (not shown), and includes a front pillar inner 2, a center pillar inner 3, and a side sill 4 at both ends in the vehicle width direction (the front pillar outer and center pillar outer are not shown). Fig. 1 shows the side sill 4 in an exploded state.

(Side sill explanation)
The side sill 4 according to this embodiment is formed into a cylindrical shape extending in the longitudinal direction of the vehicle body by combining two parts. A shock absorbing member 6 that cooperates with the side sill 4 to form the side sill structure 5 of the present invention is housed inside the side sill 4. The shock absorbing member 6 will be described in detail later.
The two components that make up the side sill 4 are a side sill inner 7 that extends in the fore-aft direction of the vehicle body on the inside of the vehicle body, and a side sill outer 8 that extends in the fore-aft direction of the vehicle body on the outside of the vehicle body. As shown in Fig. 2, the side sill inner 7 and the side sill outer 8 each have a main body 7a, 8a that has a U-shaped cross section, and upper flanges 7b, 8b and lower flanges 7c, 8c for welding that are formed integrally with the ends of the main bodies 7a, 8a.

The side sill inner 7 is welded to a floor panel (not shown) and a cross member 11 of the vehicle body frame 1 with the open portion of the U-shaped main body 7a facing toward the outside of the vehicle body.
The side sill outer 8 is welded to the side sill inner 7 with the open portion of the U-shaped main body 8a facing toward the inside of the vehicle body.
The upper flanges 7b, 8b of the side sill inner 7 and the side sill outer 8 protrude upward from the upper ends of the main bodies 7a, 8a when mounted on the vehicle. The lower flanges 7c, 8c protrude downward from the lower ends of the main bodies 7a, 8a when mounted on the vehicle. These upper flanges 7b, 8b and lower flanges 7c, 8c extend from the front end to the rear end of the side sill inner 7 and the side sill outer 8. The welding of the side sill inner 7 and the side sill outer 8 is performed by overlapping the upper flanges 7b, 8b of the side sill inner 7 and the side sill outer 8 with each other and spot welding them, and by overlapping the lower flanges 7c, 8c with each other and spot welding them.

The shock absorbing member 6 is intended to absorb the shock applied to the side sill 4 from the side of the vehicle body, and in this embodiment extends from the front end to the rear end within the side sill 4. However, costs can be reduced by setting the length of the shock absorbing member 6 to a location and length appropriate for the side collision test.
A retaining member 12 for supporting the impact absorbing member 6 within the side sill 4 is welded to the lower end of the impact absorbing member 6, and a center pillar inner connecting piece 13 for connecting to the lower end of the center pillar inner 3 is welded to the upper end of the impact absorbing member 6. Although not shown, the center pillar inner 3 is equipped with a center pillar outer and forms a closed cross section extending vertically.
The retaining member 12 extending downward from the impact absorbing member 6 is sandwiched between the lower flanges 7c, 8c and fixed to these lower flanges 7c, 8c by spot welding. Also, the center pillar inner connecting piece 13 extending upward from the impact absorbing member 6 is sandwiched between the upper flanges 7b, 8b and fixed to these upper flanges 7b, 8b by spot welding, thereby reliably fixing the lower part of the center pillar inner 3 via the impact absorbing member 6.

(Explanation of shock absorbing components)
As shown in Figures 3(A) and (B), the impact absorbing member 6 comprises a plurality of hollow bodies 14 arranged at predetermined intervals in the front-rear direction of the vehicle body (the direction from left to right in Figures 3(A) and (B)}, and a plurality of connecting pieces 15 that connect these hollow bodies 14 together. Figure 3(A) is a perspective view of the impact absorbing member 6, and Figure 3(B) is a front view of a portion of the impact absorbing member 6 as seen from the side of the vehicle body.

The hollow body 14 has a shape in which a closed cross section 16 is formed when viewed from the side of the vehicle body, and is formed in a cylindrical shape extending in the vehicle width direction. The hollow body 14 in this embodiment is formed in a square cylindrical shape in which the closed cross section 16 has a parallelogram shape. Here, for convenience, in order to identify the multiple hollow bodies 14, they are referred to as the first hollow body 14A, the second hollow body 14B, the third hollow body 14C, the fourth hollow body 14D, the fifth hollow body 14E, and the sixth hollow body 14F in order from the front side to the rear side of the vehicle body in FIG. 3(A).

The connecting piece 15 is formed in a plate shape extending in the longitudinal direction and width direction of the vehicle body, and connects two adjacent hollow bodies 14 at a position offset vertically with respect to the hollow body 14, i.e., at a position biased in the vertical direction. When three or more hollow bodies 14 are provided and there are multiple connecting pieces 15 in the longitudinal direction of the vehicle body as shown in Figures 3(A) and 3(B), the vertical positions of the connecting pieces 15 are alternately distributed in the longitudinal direction of the vehicle body. That is, the connecting piece 15 connecting the first hollow body 14A and the second hollow body 14B connects the upper ends of the first and second hollow bodies 14A and 14B, while the connecting piece 15 connecting the second hollow body 14B and the third hollow body 14C connects the lower ends of the second and third hollow bodies 14B and 14C.

The hollow body 14 and the connecting piece 15 described above are formed by combining the first and second closed cross-sectional half parts 17, 18 shown in Fig. 4(A) and (B) with each other as shown in Fig. 4(C) to form a closed cross-sectional body 19. Fig. 4(A) is a perspective view showing the first closed cross-sectional half part 17, Fig. 4(B) is a perspective view showing the second closed cross-sectional half part 18, and Fig. 4(C) is a cross-sectional view of the closed cross-sectional body 19.
The first closed cross-sectional half 17 and the second closed cross-sectional half 18 are each formed into a hat-shaped cross-section by pressing a steel plate, and each has two functional parts.

The first functional part is a hat part 17a, 18a formed in an approximately U-shape located in the center of the vehicle body in the front-rear direction (left-right direction in Figs. 4(A) and (B)). The hat part 17a, 18a has a flat top 21 and a pair of inclined walls 22 connected to both front and rear ends of the hat part and extending in the vertical direction. The top 21 is formed flat so as to extend horizontally. The pair of inclined walls 22 form the sides of the hat part 17a, 18a, and are inclined in a direction in which the distance between the inclined walls 22 gradually increases as they move away from the top 21, making press molding easier. The tip part of the inclined wall 22 forms a flange part that is bent to be parallel to the top 21 in order to connect to the second functional part described later. The inclined wall 22 of the first closed cross-sectional half part 17 shown in Fig. 4(A) extends upward from the top 21. The inclined wall 22 of the second closed cross-sectional half 18 shown in FIG. 4(B) extends downward from the top 21.

5(A) and 5(B), a (sill outer) fixing member 23 can be provided on the inclined wall 22. The (sill outer) fixing member 23 is for connecting the impact absorbing member 6 to the side sill outer 8 or the side sill inner, and is formed in a plate shape and extends from one inclined wall 22 toward the other inclined wall 22 (toward the outside of the closed cross section 16).
There are two methods for providing the (sill outer) fixing member 23 to the inclined wall 22. The first method is to form it integrally with the inclined wall 22 as shown in Fig. 5(A). The second method is to form it separately from the inclined wall 22 and weld it to the inclined wall 22 as shown in Fig. 5(B).

The second functional portion is a pair of flange portions 17b, 18b (see FIGS. 4(A) and (B)) protruding from both ends of the hat portions 17a, 18a in the longitudinal direction of the impact absorbing member 6. The flange portions 17b, 18b constitute the upper and lower ends of the hollow body and the connecting piece 15, and are formed in the shape of flat plates extending horizontally, protruding from the tip (lower end or upper end) of the inclined wall 22 in the fore-and-aft direction of the vehicle body.
The first closed cross-sectional half 17 and the second closed cross-sectional half 18 may have the same shape or different shapes. For example, depending on the required shock absorbing form, the number of hat portions on one side may be greater than the other, the length, thickness, and strength of the top 21 and the inclined wall 22 may be increased or decreased, or the shape may be changed. Of course, if the first closed cross-sectional half 17 and the second closed cross-sectional half 18 have the same shape, only one press mold is required, which reduces equipment costs.

The first closed cross-section half 17 and the second closed cross-section half 18 are joined together in such a manner that the convex directions of the first closed cross-section half 17 and the second closed cross-section half 18 are opposite in the vertical direction, and the apex 21 of the first closed cross-section half 17 and the second closed cross-section half 18 overlap with the tip of one of the flanges 17b, 18b, as shown in FIG. 4(C). FIG. 4(C) shows a state in which the apex 21 of the first closed cross-section half 17 overlaps with the tip of the flange 18b on the front side of the vehicle body of the second closed cross-section half 18, and the tip of the flange 17b on the rear side of the vehicle body of the first closed cross-section half 17 overlaps with the apex 21 of the second closed cross-section half 18.

The first closed cross-section half 17 and the second closed cross-section half 18 are joined by spot welding at the two overlapping portions described above. By joining the first closed cross-section half 17 and the second closed cross-section half 18 in this manner, a closed cross-section body 19 is formed, and a closed cross section 16 (hollow body) is formed, which is made up of the inclined walls 22, 22 of the opposing hat portions 17a, 18a of the first and second closed cross-section half portions 17, 18 and the opposing brim portions 17b, 18b.

(Description of manufacturing method of impact absorbing member)
There are four methods for manufacturing the impact absorbing member 6 extending in the longitudinal direction of the vehicle body using the first closed cross-sectional half portion 17 and the second closed cross-sectional half portion 18, as described below.
The first manufacturing method is carried out as shown in the flowchart of Fig. 7. First, as shown in step S1 of the flowchart of Fig. 7, the first closed cross-sectional half 17 and the second closed cross-sectional half 18 are press-molded, respectively (see Fig. 8(A)). If the sill outer fixing member 23 is integrally formed with the first and second closed cross-sectional half 17, 18, the sill outer fixing member 23 is bent in the longitudinal direction of the shock absorbing member 6 in this process.
If the sill outer fixing member 23 is to be welded to the first closed cross-section half 17 and the second closed cross-section half 18, this is carried out in this process.

Next, as shown in FIG. 8(B), the first closed cross-section half 17 and the second closed cross-section half 18 are combined and welded to form a closed cross-section body 19 (step S2). The number of closed cross-section bodies (hollow bodies) 19 is formed according to the length of the impact absorbing member 6. For example, as shown in FIG. 8(D), the blank may be press-formed so that the first closed cross-section half 17 and the second closed cross-section half 18 are arranged with two hat portions 17a and 18a lined up. Then, as shown in FIG. 8(C), a plurality of closed cross-section bodies 19 are lined up in a row in the front-rear direction of the vehicle body, and adjacent closed cross-section bodies 19 are welded together. At this time, the tops 21 of the hat portions 17a and 18a and the brim portions 17b and 18b are overlapped, and the overlapping portions are welded by spot welding (step S3). By joining a plurality of closed cross-section bodies 19 in this way, a long impact absorbing member 6 is completed.

The second manufacturing method is carried out as shown in the flowchart of FIG. 9. First, as shown in step S11 of the flowchart of FIG. 9, the first closed cross-section half 17 and the second closed cross-section half 18 are formed. The first closed cross-section half 17 and the second closed cross-section half 18 are formed as shown in FIG. 8(A). Next, as shown in the first intermediate part formation step S12 of the flowchart and FIG. 10, the upper first intermediate part 31 and the lower first intermediate part 32 are formed. At this time, a plurality of first closed cross-section half parts 17 are arranged in the longitudinal direction of the vehicle body, and adjacent first closed cross-section half parts 17 are welded to each other to form the upper first intermediate part 31 as an intermediate part. Also, a plurality of second closed cross-section half parts 18 are arranged in the longitudinal direction of the vehicle body, and adjacent second closed cross-section half parts 18 are welded to each other to form the lower first intermediate part 32 as an intermediate part. The first intermediate parts 31 and 32 do not have a closed cross section.

Then, the upper first intermediate part 31 and the lower first intermediate part 32 are assembled in such a manner that the convex directions of the cap parts are opposite to each other, and the top of the cap part of one closed cross-section half part is overlapped and joined to the brim part of the other closed cross-section half part (shock absorbing member forming step S13). At this time, the top 21 of the cap part 17a of the first intermediate part 31 of the upper divided body is welded to the brim part 18b of the lower first intermediate part 32 by spot welding, and the brim part 17b of the upper first intermediate part 31 is welded to the top 21 of the cap part 18a of the lower first intermediate part 32 by spot welding. In this way, the intermediate parts, the upper first intermediate part 31 and the lower first intermediate part 32, are joined to each other, thereby completing the long shock absorbing member 6.

The third manufacturing method is carried out as shown in the flowchart of FIG. 11. First, as shown in step S21 of the flowchart of FIG. 11, the first closed cross-sectional half 17 and the second closed cross-sectional half 18 are formed, respectively. The first closed cross-sectional half 17 and the second closed cross-sectional half 18 are formed as shown in FIG. 8(A). Next, as shown in FIG. 12, the first closed cross-sectional half 17 and the second closed cross-sectional half 18 are combined in such a manner that the convex directions of the hat portions are opposite to each other, and the top of the hat portion of one closed cross-sectional half is overlapped and joined to the brim portion of the other closed cross-sectional half to form at least two or more second intermediate parts 33 (second intermediate part formation step S22). The second intermediate part 33 has a closed cross section. In FIG. 12, the second intermediate part 33A and the second intermediate part 33B are illustrated. After that, the second intermediate part 33A and the second intermediate part 33B are lined up in the front-rear direction and welded to each other (shock absorbing member forming step S23). In this way, the second intermediate part 33A and the second intermediate part 33B, which are intermediate parts, are joined to each other, thereby completing the long-shaped shock absorbing member 6.

The fourth manufacturing method is carried out as shown in the flowchart of FIG. 13. First, as shown in step S31 of the flowchart of FIG. 13, the first closed cross-sectional half 17 and the second closed cross-sectional half 18 are formed. The first closed cross-sectional half 17 and the second closed cross-sectional half 18 are formed as shown in FIG. 8(A). Next, as shown in step S32 of the flowchart and FIG. 14, the shock absorbing member 6 is formed. At this time, the closed cross-sectional half parts constituting the shock absorbing member 6 are assembled in a state where the closed cross-sectional half parts are not joined to each other, with the adjacent cap parts being in opposite convex directions, and the top of the cap part of the closed cross-sectional half part is overlapped and joined to the brim part of the adjacent closed cross-sectional half part in the opposite orientation to this closed cross-sectional half part, thereby completing the long shock absorbing member 6. The top of the cap part of the closed cross-sectional half part may be overlapped and joined to the brim parts of the adjacent closed cross-sectional half parts on both sides in the opposite orientation to this closed cross-sectional half part.

(Description of the manufacturing method of the side sill)
The process for manufacturing the side sill 4 having the impact absorbing member 6 formed in a long shape is as shown in the flow chart of Fig. 15. First, as shown in Fig. 16(A), the retaining member 12 and the center pillar inner connecting piece 13 are joined to the impact absorbing member 6 (step S41). If the (sill outer) fixing member 23 is to be welded to the first and second closed cross-sectional half portions 17, 18 of the impact absorbing member 6, this is carried out in this process.

Next, as shown in FIG. 16(B), the side sill outer 8 is joined to the shock absorbing member 6 (step S42). This joining is performed by welding the side sill outer 8 to the (sill outer) fixing member 23. Then, as shown in FIG. 16(C), the side sill outer 8 to which the shock absorbing member 6 is joined is joined to the side sill inner 7 (step S43). This joining is performed by overlapping the upper flange 7b and the lower flange 7c of the side sill inner 7 with the upper flange 8b and the lower flange 8c of the side sill outer 8, and spot welding them. When this joining is performed, the retaining member 12 and the center pillar inner joint piece 13 are sandwiched between the flanges, and these members are also joined to the flanges at the same time. The side sill outer 8 is joined to the side sill inner 7, completing the side sill 4. At this time, the center pillar inner joint piece 13 is also joined to the lower end of the side sill inner 7.

(Description of another manufacturing method for side sill)
The manufacturing method of the side sill 4 having the impact absorbing member 6 formed in a long shape can be performed as shown in the flow chart of FIG. 17. In the manufacturing method of this side sill 4, first, in step S51, the impact absorbing member 6 is joined to the side sill inner 7. In this case, a sill inner fixing member (not shown) equivalent to the sill outer fixing member 23 is provided in advance on the impact absorbing member 6, and the sill inner fixing member is welded to the side sill inner 7 in step S51. Next, in step S52, the side sill outer 8 is welded to the side sill inner 7. In this step S52, the holding member 12 and the center pillar inner joint piece 13 are sandwiched between the upper flange 7b and the lower flange 7c of the side sill inner 7 and the upper flange 8b and the lower flange 8c of the side sill outer 8, and these members are spot welded at the same time. The side sill outer 8 is joined to the side sill inner 7 to complete the side sill 4.
By using this manufacturing method and joining the impact absorbing member 6 to the side sill inner 7, it becomes easy to align it so that the load can be transmitted to the rigid member (cross member) on the floor side.

(Explanation of Effects of This Embodiment)
As shown in Fig. 18, the shock absorbing member 6 according to this embodiment includes at least two hollow bodies 14 arranged at a predetermined interval in the longitudinal direction of the vehicle body with a closed cross section 16 extending in the vehicle width direction, and connection pieces 15 (flange portions 17b, 18b, top portion 21) that connect adjacent hollow bodies 14 at positions offset in the vertical direction (positions biased in the vertical direction) with respect to the hollow bodies 14. When there are multiple connection pieces 15 in the longitudinal direction of the vehicle body, the vertical positions of the connection pieces 15 are alternately distributed in the longitudinal direction of the vehicle body. This shock absorbing member 6 is configured such that the connection pieces 15 (flange portions 17b, 18b) are offset in the vertical direction with respect to the centroid A of the hollow body 14 as viewed from the side, and are significantly separated from the centroid A. Therefore, the moment of inertia is increased compared to the case where the connection pieces 15 are located at the same height as the centroid A of the hollow body 14.

Furthermore, the pair of hollow bodies 14, 14 are shaped like a V, which further increases the strength of the connection piece 15, allowing the connection piece 15 to firmly receive the impact load at an offset position and crush the shock absorbing member 6 from the outside and tip. Because this V shape is formed by overlapping alternately in the front-to-rear direction, it is possible to absorb the impact of a side impact load not only from directly to the side, but also from any inclined input such as upward, downward, forward, or backward.

In addition, because the connecting pieces 15 are offset in the vertical direction with respect to the centroid A of the hollow body 14, the connecting pieces 15 come closer to the upper corners 41 and lower corners 42 of the side sill inner 7 as shown in Fig. 19. Because the upper corners 41 and lower corners 42 of the side sill inner 7 are corners, they have higher rigidity in the vehicle width direction compared to other parts, as compared to flat portions.
Therefore, compared to when the connecting piece 15 is not offset in the vertical direction, during a collision in which an impact load is applied to the side sill 4 from the side of the vehicle body, i.e., during a side collision, the vertical surface of the side sill inner 7 is less likely to bend, and as shown by the two-dot chain line in Figure 20, deformation 43 progresses from the end on the outer side of the vehicle body gradually toward the inner side of the vehicle body, causing the shock absorbing member 6 to collapse. As a result, the amount of impact energy absorbed increases.

In addition, the connection pieces 15 are offset in the vertical direction from the centroid A of the hollow body 14, so that the upper and lower surfaces of the hollow body 14 and the upper and lower connection pieces 15 are closer to the upper and lower corners of the side sill inner 7. The upper and lower corners of the side sill inner 7 have high rigidity and strength, and the side impact load is also dispersed vertically, so that the side sill inner 7 braces itself against the side impact load, suppressing the movement of the shock absorbing member 6 toward the inside of the vehicle, and the shock absorbing member 6 is crushed from the end on the outside of the vehicle body toward the inside of the vehicle body, helping to increase the amount of impact energy absorbed {see FIG. 21(A), ⇒ indicates the amount of movement}. Furthermore, although not shown in the figure, it also comes closer to the floor below and the cross member above, so that the movement of the shock absorbing member 6 toward the inside of the vehicle is further suppressed.
On the other hand, if the connecting piece 15 is not offset in the vertical direction but is in the center, as shown in Figure 21 (B), the side sill inner 7 will undergo out-of-plane deformation during a side collision, and the impact absorbing member 6 will move toward the inside of the vehicle cabin, or the impact absorbing member 6 will tilt within the side sill 4, making its posture unstable and preventing it from gradually progressing from the end on the outside of the vehicle body toward the inside of the vehicle body and being crushed.

The hollow body 14 and the connecting piece 15 of the shock absorbing member 6 according to this embodiment are formed by combining a pair of closed cross-sectional half parts (a first closed cross-sectional half part 17 and a second closed cross-sectional half part 18). The closed cross-sectional half part is composed of a hat part 17a, 18a formed in a U-shape and a pair of brim parts 17b, 18b protruding from both ends of the hat part 17a, 18a in the longitudinal direction of the shock absorbing member 6. The pair of closed cross-sectional half parts are joined together in such a manner that the convex directions of the hat parts 17a, 18a are opposite in the vertical direction, and the tops 21 of the hat parts 17a, 18a overlap with one of the brim parts 17b, 18b. The closed cross section 16 is formed by the side parts (inclined walls 22) of the hat parts 17a, 18a facing each other and the brim parts 17b, 18b facing each other of the pair of closed cross-sectional half parts.

For this reason, the smallest unit of the press forming process for manufacturing the impact absorbing member 6 is the closed cross-section half 17, 18 having one cap 17a, 18a, making press forming of the steel plate easy. This is because the inclined wall 22 does not create an undercut during press forming. This press forming process may also be performed with two or more caps, for example, a part with two closed cross-section half 17 arranged in the longitudinal direction of the vehicle body, as the smallest unit. In this embodiment, as shown in FIG. 3B, multiple closed cross-section half parts are combined so that the flanges 17b, 18b (connecting pieces 15) are distributed up and down in the longitudinal direction of the vehicle body, so that the number of steel plates in the spot welded part is three, between the top 21 and the flanges 17b, 18b. This increases the reliability of the spot welding.

The automobile side sill structure 5 according to this embodiment includes a sill outer fixing member 23 that protrudes outward from the closed cross section 16 of the impact absorbing member 6 as shown in FIG. 6(A), and a side sill outer 8 that is joined to the sill outer fixing member 23 in a state in which the impact absorbing member 6 is surrounded from the outside of the vehicle body as shown in FIG. 2. When the sill outer fixing member 23 extends toward the inside of the closed cross section 16 as shown in FIG. 6(B), the adjacent sill outer fixing members 23 interfere with each other. Therefore, in this case, in order to avoid interference between the sill outer fixing members 23, the closed cross section 16 must be expanded in the front-rear direction of the vehicle body to a size that does not cause the sill outer fixing members 23 to interfere with each other. This reduces the number of closed cross sections 16 in the entire impact absorbing member 6, and the amount of energy absorbed by the impact absorbing member 6 during a side collision decreases. However, since the sill outer fixing member 23 according to this embodiment extends toward the outside of the closed cross section 16 as shown in FIG. 6(A), interference between the sill outer fixing members 23 can be prevented without reducing the amount of energy absorbed by the impact absorbing member 6 during a side collision.

2, the automobile side sill structure 5 according to this embodiment includes a side sill inner 7 that surrounds the shock absorbing member 6 from the inside of the vehicle body, a side sill outer 8 that surrounds the shock absorbing member 6 from the outside of the vehicle body, and a retaining member 12 that supports the shock absorbing member 6 from below. Because of this, the shock absorbing member 6 can be held in a stable state within the side sill 4, so that when an impact is applied to the side sill 4 from the side of the vehicle body, the shock absorbing member 6 does not tilt or roll over, but instead deforms so that the upper and lower surfaces of the shock absorbing member 6 buckle to absorb the impact.
In addition, since the impact absorbing member 6 can be held without being joined to the side sill inner 7, manufacturing is facilitated.
Therefore, it is possible to easily realize a side sill structure 5 that is strong against side collisions.

In this embodiment of the automobile side sill structure 5, as shown in FIG. 2, the center pillar inner 3 is joined to the upper surface of the impact absorbing member 6. This allows the impact energy to be transmitted from the impact absorbing member 6 to the center pillar inner 3, resulting in a side sill structure 5 that is even stronger against side collisions.

Although not shown, the shock absorbing member 6 according to this embodiment can be joined to the side sill inner 7. In other words, by firmly joining the shock absorbing member 6 to the side sill inner 7 with adhesive or the like, a side sill structure 5 with further improved strength can be realized.

As shown in Figs. 7 and 8, the method for manufacturing the shock absorbing member 6 includes step S1 of forming multiple closed cross-sectional half parts (first closed cross-sectional half part 17 and second closed cross-sectional half part 18), step S2 of forming a closed cross-sectional body 19, and step S3 of combining multiple closed cross-sectional bodies 19 to form a long shock absorbing member 6. This allows the shock absorbing member 6 to be manufactured by combining multiple closed cross-sectional half parts, which are the smallest components, and therefore shock absorbing members 6 of various shapes and lengths can be manufactured. In addition, since each closed cross-sectional half part can be replaced when a defective product occurs, the yield rate when a defective product occurs is high. Furthermore, the press mold for forming the steel plate into a predetermined shape can be small, so the manufacturing cost of the equipment required for manufacturing can be kept low.

As shown in Figs. 9 to 12, the manufacturing method of the shock absorbing member 6 includes steps S11 and S21 for forming a closed cross-sectional half portion, a first intermediate part forming step S12 and a second intermediate part forming step S22 for joining a plurality of closed cross-sectional half portions to form intermediate parts (upper first intermediate part 31, lower first intermediate part 32, and second intermediate part 33), and a shock absorbing member forming step S13 and S23 for joining a plurality of intermediate parts to form a long shock absorbing member 6. In other words, when manufacturing the shock absorbing member 6 by arranging a required number of small parts, a positioning jig is required for each small part, and a large number of positioning pins are required. However, when manufacturing the shock absorbing member 6 by welding a plurality of intermediate parts to each other as in this embodiment, the number of positioning jigs and positioning pins is reduced, and therefore welding is easier as described above.

As shown in Figures 13 and 14, by adopting a method for manufacturing the shock absorbing member 6 that includes step S31 of forming multiple closed cross-sectional half portions (first closed cross-sectional half portion 17 and second closed cross-sectional half portion 18) and step S32 of forming the long shock absorbing member 6, the long shock absorbing member 6 can be formed in the next step after the closed cross-sectional half portions are formed, without going through the molding step of the intermediate parts. This eliminates the need for welding equipment such as welding jigs to form the intermediate parts, and allows the shock absorbing member 6 to be manufactured at low cost. In addition, productivity is improved because the step of molding the intermediate parts is omitted.

As shown in FIG. 15, the manufacturing method of the side sill 4 according to this embodiment is a method carried out by step S42 of joining the shock absorbing member 6 to the side sill outer 8, and step S43 of joining the side sill outer 8 to which the shock absorbing member 6 is joined and the side sill inner 7. Therefore, the side sill inner 7 can be welded to the body frame 1 of the automobile in advance and supported by the body frame 1, so that alignment can be easily performed when welding the shock absorbing member 6 and the side sill outer 8 to the side sill inner 7. As a result, the work of mounting the side sill 4 to the vehicle body is facilitated.

Second Embodiment
The shock absorbing member 6 can be configured as shown in Figs. 22(A), (B) to 24(A) to (E). Fig. 22(A) is a perspective view showing the first closed cross-sectional half 17, and Fig. 22(B) is a perspective view showing the second closed cross-sectional half 18. Fig. 23(A) is a perspective view showing another embodiment of the shock absorbing member, and Fig. 23(B) is a perspective view showing the upper and lower surfaces of the hollow body and the vertical position of the connecting piece. Fig. 24(A) shows an example in which two corners are provided on each of the upper and lower sides of the closed cross-section 16, Figs. 24(B) to (D) show an example in which six corners are provided on each of the upper and lower sides of the closed cross-section 16, and Fig. 24(E) shows an example in which five corners are provided on each of the upper and lower sides of the closed cross-section 16. In Figs. 22 to 24, the same or equivalent members as those described in Figs. 1 to 21 are given the same reference numerals and detailed description is omitted as appropriate.

The first and second closed cross-sectional half portions 17, 18 shown in Figures 22(A) and (B) have a groove 52 with two corners 51, 51 between the hat portion 17a, 18a and the flange portion 17b, 18b, which is press-formed. The groove 52 with the corners 51 is formed by press-forming the base end portion (the end portion on the hat portion 17a, 18a side) of the flange portion 17b, 18b in a direction in which the height of the hat portion 17a, 18a increases. The corners 51 located on both sides of this groove 52 have ridge lines 53 that extend in the vehicle width direction. Hereinafter, the corners 51 with the ridge lines 53 will be simply referred to as "corner ridges 51".

When the first closed cross-section half 17 and the second closed cross-section half 18 having this ridge 51 are combined, as shown in FIG. 23(A), two ridges 51 are provided on each of the upper and lower sides of the closed cross-section 16. As shown in FIG. 23(B), the closed cross-section constructing body 19 according to this embodiment has a connecting piece 15 aligned with the upper surface 14a or the lower surface 14b of the hollow body 14. The upper surface 14a and the connecting piece 15 are offset vertically by dimension A. The lower surface 14b and the connecting piece 15 are offset vertically by dimension B. The upper surface 14a, the lower surface 14b, and the connecting piece 15 are arranged in the longitudinal direction along the side sill inner 7 in this vertically offset state.

The shock absorbing member 6 to which the corner ridges 51 are added in this way has a larger energy absorption capacity than the shock absorbing member 6 in the first embodiment. This is because the corner ridges 51 have a higher strength, and therefore the energy required to buckle them increases.
Although not shown, the corner ridge 51 may be provided only on either the upper side or the lower side of the closed cross section 16. The energy absorption amount of the impact absorbing member 6 can be increased by merely forming the groove 52 during press molding.

The corner ridges 51 can be provided as shown in Figures 24(A) to 24(E). That is, as shown in Figure 24(A), the corner ridges 51 can be provided at both ends of the upper and lower sides of the closed cross section 16 by forming a groove 52 by recessing the grooves 52 to form the upper and lower sides so that the closed cross section 16 is expanded in the vertical direction. Alternatively, as shown in Figure 24(B), the corner ridges 51 can be provided at six points each on the upper and lower sides by forming two grooves 52 by press forming the grooves 52 to form the upper and lower sides so that the closed cross section 16 is expanded in the vertical direction, and recessing the centers of the upper and lower sides inwardly of the closed cross section 16 in a rectangular cross section.
Figure 24 (C) shows an example in which a step shape is added to one side of the groove 52 to form the upper and lower edges so that the closed cross section 16 is expanded in the vertical direction, and the upper and lower edges are formed in a stepped shape to provide six corner edges 51 on each of the upper and lower sides.

Figure 24 (D) shows an example in which a small groove is press-molded into the bottom surface of groove 52 to form upper and lower edges so that the closed cross section 16 is expanded in the vertical direction, and the centers of the upper and lower edges are protruded outside the closed cross section 16 in a rectangular cross-sectional shape to provide six corner edges 51 on each of the upper and lower sides.
Figure 24 (E) shows an example in which the center of the bottom surface of groove 52 is press-molded to raise the center, forming upper and lower edges so that closed cross section 16 is expanded in the vertical direction, and the centers of the upper and lower edges are recessed into a V-shaped cross section to provide five corner edges 51 on each of the upper and lower sides.

1...vehicle body frame for automobile, 3...center pillar inner, 5...side sill structure, 6...shock absorbing member, 7...side sill inner, 8...side sill outer, 12...retaining member, 14...hollow body, 15...connecting piece, 16...closed section, 17...first closed section half, 18...second closed section half, 17a, 18a...cap portion, 17b, 18b...brim portion, 21...top, 23...(sill outer) fixing member, 51...corner, corner ridge, 52...groove, 53...ridge line, S1, S11, S21, S31...step of forming a plurality of closed section half portions, S2...step of forming a closed section body, S3... Step of forming a long impact absorbing member, S12, S22... Step of forming intermediate parts, S13, S23... Step of joining intermediate parts together to form a long impact absorbing member, S32... Step of joining closed cross-sectional half parts together to form an impact absorbing member, S42... Step of joining the side sill outer to the impact absorbing member, S43... Step of joining the side sill outer and the side sill inner, S51... Step of joining the impact absorbing member to the side sill inner, S52... Step of joining the side sill outer to the side sill inner.

Claims (6)

A closed cross-sectional half forming step of press-forming a steel plate blank into a hat-shaped cross section having a top of a hat portion, a pair of inclined walls, a pair of grooves including the inclined walls, and a flange portion to form a closed cross-sectional half;
a closed cross section constituent forming step of combining at least three or more of the closed cross section constituent halves in such a manner that the convex directions of the cap portions are opposite to each other, overlapping and joining the top of the cap portion of one of the closed cross section constituent halves and the brim portion of the other of the closed cross section constituent halves so as to extend in the longitudinal direction, which is the direction in which the brim portion protrudes from the cap portion , to form a plurality of closed cross section constituents consisting of upper and lower grooves including the inclined walls of the cap portion and connected by connecting pieces formed by overlapping the brim portion and the top in the thickness direction only in the longitudinal direction;
A shock absorbing member is formed by
The closed cross section constituent is a cylindrical hollow body extending in a direction perpendicular to the longitudinal direction, has the connection piece between adjacent hollow bodies, and is arranged in plurality in the longitudinal direction,
A manufacturing method for an impact absorbing member, characterized in that the hollow body forms a closed cross-section by the upper and lower grooves, and the upper and lower edges of the closed cross-section each have at least two or more angular edges extending in a direction perpendicular to the longitudinal direction. The method for manufacturing the shock absorbing member of claim 1, further comprising adding one or more of the following to the groove: a step shape, a smaller groove, two or more smaller second grooves, a raised portion, or a V-shaped recess in cross section. The method for manufacturing the shock absorbing member of claim 1 has fixing members that protrude outward from the inclined walls of the hat portions that face each other in the closed cross-sectional half of the shock absorbing member. A step of joining an impact absorbing member formed by the impact absorbing member manufacturing method according to any one of claims 1 to 3 to a side sill outer;
and joining the side sill outer and the side sill inner to which the impact absorbing member is joined. A step of joining an impact absorbing member formed by the impact absorbing member manufacturing method according to any one of claims 1 to 3 to a side sill inner;
and joining the side sill inner to which the impact absorbing member is joined and the side sill outer. a shock absorbing member is formed by combining at least three or more closed cross section half sections each having a hat-shaped cross section, the closed cross section half sections having a top of a hat section, a pair of inclined walls, a pair of grooves including the inclined walls, and a brim, in such an orientation that the convex directions of the hat section are opposite to each other, and overlapping and joining the top of the hat section of one of the closed cross section half sections and the brim section of the other closed cross section half section so as to extend in the longitudinal direction, which is the direction in which the brim section protrudes from the hat section , to form a shock absorbing member that forms a plurality of closed cross section constituents consisting of upper and lower grooves including the inclined walls of the hat section and connected only in the longitudinal direction by a connecting piece formed by overlapping the brim section and the top in the thickness direction ,
The closed cross section constituent is a cylindrical hollow body extending in a direction perpendicular to the longitudinal direction, has the connection piece between adjacent hollow bodies, and is arranged in plurality in the longitudinal direction,
The hollow body has a closed cross section formed by the upper and lower grooves, and each of the upper and lower edges of the closed cross section has at least two or more angular edges extending in a direction perpendicular to the longitudinal direction .

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