JP6268780B2 - Columnar member - Google Patents

Description

  The present invention relates to a thin-walled columnar member used for an automobile body or the like.

2. Description of the Related Art In order to reduce the weight and rigidity of a vehicle, an automobile forms a vehicle body by welding columnar members formed by plastically deforming thin plates so that the cross section has a so-called hat shape. Further, in order to secure a living space in the passenger compartment in the event of a car crash, such a columnar member is required to suppress a sudden decrease in reaction force during bending deformation and increase absorbed energy.

  For example, in Patent Document 1, a plurality of convex portions are provided on a pair of opposite side surfaces (wall surface portions), and the bending resistance characteristics are further improved by suppressing the outward deformation of the bending portion at the initial stage of bending deformation. A vehicle frame structure is disclosed.

JP 2011-16409 A

  However, in the vehicle frame structure described in Patent Document 1, the protrusions must be uniformly formed on the side wall, and it is very difficult to process the column member.

An object of the present invention is to solve such a problem of the prior art, and provides a columnar member having a hat-shaped cross section that suppresses a sudden decrease in reaction force during bending deformation with a simple configuration and increases the amount of absorbed energy. The purpose is that.

In order to achieve the above-mentioned object, according to the present invention, an upper wall extending along a predetermined axis, side walls extending along both side edges of the upper wall, and an upper wall at the side wall are provided. A columnar member having a flange portion extending along an edge on the side opposite to the axis and having a substantially hat-shaped cross section perpendicular to the axis, wherein the side wall is connected to the upper wall. Adjacent to the edge to a height of 0.10 to 0.40 times the side wall height, the maximum width is 0.12 to 0.80 times the side wall height, with respect to the strength of the base material Provided is a columnar member provided with a low strength portion of 0.2 or more and 0.8 or less, the low strength portion being surrounded by the base material having the strength of the base material. .

According to the present invention, by simply providing a low strength portion adjacent to a side edge portion connected to the upper wall on the side wall of a columnar member having a hat-shaped cross section, a sudden decrease in reaction force during bending deformation can be suppressed and absorbed. it is possible to increase the energy.

  Further, in the invention of Patent Document 1, the resistance force and the absorbed energy are increased only by suppressing the outward deformation of the side wall of the member. However, in the present invention, the low strength portion is crushed first. When the portions located at the ends of the low-strength portions come into contact with each other, they serve as fulcrums to resist deformation and increase the resistance and the amount of absorbed energy.

FIG. 3 is an end view of a columnar member having a hat-shaped cross section according to a preferred embodiment of the present invention as viewed in the direction of arrow I-I in FIG. 2. It is a side view of the columnar member which has the hat-shaped cross section seen in the direction of arrow II-II of FIG. It is the schematic for demonstrating the approximate dimension of the columnar member used by simulation. It is the schematic for demonstrating the collision system which performed simulation. It is a figure which shows the simulation result of the columnar member of this invention which has a low intensity | strength part. It is a figure which shows the simulation result of the columnar member of the comparative example which is not provided with the low intensity | strength part. It is a graph which shows the change of the reaction force with respect to the displacement of a striker about the columnar member of this invention and the columnar member of a comparative example. It is a graph which shows the change of the energy absorption amount with respect to the displacement of a striker about the columnar member of this invention and the columnar member of a comparative example. It is the schematic which showed the semicircle shaped low intensity | strength part. It is the schematic which showed the equilateral triangular low intensity | strength part.

A preferred embodiment of the present invention will be described below with reference to FIGS.
The columnar member 10 includes a flat plate-like upper wall 12 extending along a linear main axis Om perpendicular to the paper surface of FIG. 1 and side walls 14 extending along both side edges 12a and 12b of the upper wall 12. , 16 and flange portions 18, 20 extending along the opposite edge portions 14 a, 16 a of the side walls 14, 16, the longitudinal direction being the direction of the main axis Om of the columnar member 10 A cross section (cross section) cut along a plane perpendicular to the cross section is generally a hat shape.

  Low strength portions 22 and 24 are provided on the side walls 14 and 16 of the columnar member 10, respectively. In the embodiment shown in FIGS. 1 and 2, the low-strength portions 22 and 24 can be formed by hot stamping or partially tempering to soften a part of the side walls 14 and 16. For example, as shown in FIG. 9, the low-strength portions are semicircular low-strength portions 22 ′ and 24 having centers on the upper edges of the side walls 14 and 16, that is, the side edges 12 a and 12 b of the upper wall 12. ′, And similarly, a triangle whose top edges are arranged toward the flange portions 18 and 20 with the top edges of the side walls 14 and 16, that is, a part of the side edges 12 a and 12 b of the top wall 12 being the bottom. The low strength portions 22 ″ and 24 ″ of isosceles triangles are preferable. The low-strength portions 22 and 24 have a strength 0.8 to 0.2 times, preferably 0.7 times that of the other portions.

  Simulation (numerical analysis) of the deformation behavior of the columnar member 10 when an external force F is applied in the vertical direction along the axis O to the upper wall 12 of the columnar member 10 having a hat-shaped cross section to which the present invention is applied; A comparative example without a low strength part was compared. The comparative example has the same shape as the columnar member 10 of the present invention except that the low-strength portions 22 and 24 are not provided. The axis O is an intersection of the upper wall 12 passing through the centers of the low strength portions 22 and 24 and a plane perpendicular to the main axis Om and the side wall.

  The schematic dimensions of the columnar member 10 used in the simulation are shown in FIG. In FIG. 3, the columnar member 10 has a length of 1000 mm, a width of the upper wall 12 of 60 mm, a maximum width (distance between outer edges of the flanges 18 and 20) of 120 mm, a width of each of the flange portions 18 and 20, 20 mm, and the side walls 14 and 16. The height is 60 mm. The side walls 14 and 16 are formed with semi-circular low strength portions 22 'and 24' as shown in FIG.

  As shown in FIG. 4, the above-mentioned columnar member 10 and the columnar member of the comparative example are bridged between a pair of columns 30 and 32 as fulcrums, and a columnar rigid body 40 having a mass of 200 kg is used as a striker, as indicated by an arrow A. The deformation behavior of the columnar member 10 when it collided with the upper wall 12 was simulated. The cylinders 30 and 32 as fulcrums are 50 mm in diameter and are fixed apart from each other with a distance (span) of 700 mm between the contacts Pt1 and Pt2 with the flange portions 18 and 20 of the columnar member 10. The simulation was performed under the condition of not moving at the striker collision. The collision speed of the striker to the upper wall 12 is 10 m / s.

  The simulation results are shown in FIGS. FIG. 5 shows the deformation behavior of the columnar member 10 according to the present invention having the semicircular low strength portions 22 'and 24' as shown in FIG. 9, and FIG. 6 shows the deformation behavior of the columnar member of the comparative example. ing. When the striker 40 collides with the columnar member 10 along the axis O, the columnar member is bent and deformed so that the upper wall 12 is recessed in the advancing direction of the striker 40 regardless of the case of the present invention or the comparative example. As a result, the side walls 14 and 16 are deformed into a substantially square shape while bulging outward, and as a result, the columnar member 10 is deformed so as to be bent around the axis O so as to be recessed in the direction of the arrow A. At that time, in the columnar member 10 according to the present invention, when the striker 40 collides, the deformation starts from the low strength portions 22 ′ and 24 ′, and both ends P 1 and P 2 of the semicircular arc approach each other, and finally Contact is made at one point Pa (contact point Pa, see FIG. 5). Then, the contact point Pa serves as a fulcrum, and the side walls 14 and 16 are hardly deformed and the movement (displacement) of the striker 40 is prevented. On the other hand, in the comparative example, the deformation of the side wall proceeds, and the side wall is bent greatly compared to the columnar member according to the present invention.

  FIG. 7 shows a change in the reaction force with respect to the displacement of the striker 40. In the columnar member according to the comparative example, the reaction force gradually decreases with respect to the displacement of the striker 40, and the reaction force increases because the side walls of the columnar member deformed into a substantially square shape contact each other at the final stage. In the columnar member, the reaction force increases early when the side wall comes into contact with the point Pa, and the displacement of the striker 40 is also smaller than in the comparative example.

  FIG. 8 shows the energy absorption amount of the columnar member 10 with respect to the displacement of the striker 40 in the axis O direction. It will be understood from FIG. 8 that the columnar member 10 according to the present invention absorbs the same energy with a smaller displacement than the columnar member according to the comparative example.

Further, by changing the radius r of the semi-circular low strength portions 22 'and 24' provided on the side walls 14 and 16, a simulation was performed in the same system as in FIG. 4, and the changes in the maximum reaction force and the absorbed energy were compared. The comparison results are shown in Table 1. In Table 1, the radius r is standardized by the height H of the side walls 14 and 16.

  From Table 1, the columnar members (B, C) in which the radius R of the low-strength portions 22 ′, 24 ′ is 20 to 40% with respect to the height H of the side walls 14, 16, particularly 20% of the columnar members (B). It will be understood that the maximum reaction force and the amount of absorbed energy are high in the case of. On the other hand, when the radius R is 50% (columnar member D) with respect to the height H of the side walls 14 and 16, the maximum reaction force and the amount of absorbed energy are both less than when the low strength portions 22 'and 24' are not provided. It will decline.

Further, the strength of the semicircular low strength portions 22 'and 24' provided on the side walls 14 and 16 was changed, and a simulation was performed in the same system as in FIG. 4 to compare the changes in the maximum reaction force and the absorbed energy. The comparison results are shown in Table 2. In Table 2, the strength is standardized by the strength of the base material excluding the low strength portions 22 'and 24'.

  From Table 2, in the case of the columnar members (C to F) in which the strength of the low-strength portions 22 'and 24' relative to the base material is 0.2 to 0.8, the maximum reaction force is greater than that of the columnar members (A and B). It will be understood that the amount of absorbed energy is high, although it is low. In particular, the difference between the columnar member (B) and the columnar member (C) is large, and a remarkable effect is shown.

Further, the length L of one side of the regular triangular low strength portions 22 ″ and 24 ″ provided on the side walls 14 and 16 is changed, and a simulation is performed in the same system as in FIG. 4 to change the maximum reaction force and the absorbed energy. Compared. The comparison results are shown in Table 2. In Table 2, the length L of one side is standardized by the height H of the side walls 14 and 16.

  From Table 3, columnar members (B, C) in which the length L of one side of the low-strength portions 22 ″ and 24 ″ is 10% to 28% with respect to the height H of the side walls 14 and 16, particularly 10%. It will be understood that in the case of (B), the maximum reaction force and the amount of absorbed energy are high. On the other hand, when the length L of one side is 42% (columnar member D) with respect to the height H of the side walls 14 and 16, the low strength portions 22 ″ and 24 ″ are not provided for both the maximum reaction force and the absorbed energy. It will be lower than the case.

Further, the strength of the equilateral triangular low strength portions 22 ″ and 24 ″ provided on the side walls 14 and 16 was changed, and a simulation was performed in the same system as in FIG. 4 to compare changes in maximum reaction force and absorbed energy. Table 4 shows the comparison results. In Table 4, the strength is standardized by the strength of the base material excluding the low strength portions 22 ″ and 24 ″.

  From Table 4, in the case of the columnar members (C to F) in which the strength of the low strength portions 22 ″ and 24 ″ with respect to the base material is 0.2 to 0.8, the maximum reaction force is higher than that of the columnar members (A and B). It will be understood that the amount of absorbed energy is high, although it is low. In particular, the difference between the columnar member (B) and the columnar member (C) is large, and a remarkable effect is shown.

  The present invention can be applied to the body of an automobile.

DESCRIPTION OF SYMBOLS 10 Columnar member 12 Upper wall 14 Side wall 16 Side wall 18 Flange part 20 Flange part 22 Low-strength part 24 Low-strength part 30 Cylindrical member 32 Cylindrical member 40 Striker

Claims (4)

An upper wall extending along a predetermined axis, side walls extending along both side edges of the upper wall, and a flange extending along an edge of the side wall opposite to the upper wall In a columnar member having a section, a cross section perpendicular to the axis exhibits a substantially hat shape,
The maximum width of the side wall is 0.12 to 0.80 of the side wall height up to a height of 0.10 to 0.40 times the side wall height adjacent to the side edge connected to the upper wall. In the double region, a low-strength portion of 0.2 to 0.8 with respect to the strength of the base material is provided , and the low-strength portion is surrounded by the base material having the strength of the base material. columnar member characterized by there.   2. The columnar member according to claim 1, wherein the low-strength portion is a semicircular low-strength portion disposed so that a diameter extends along an edge portion between the upper wall and the side wall.   2. The columnar member according to claim 1, wherein the low-strength portion is an isosceles triangular low-strength portion arranged so that a base extends along an edge between the upper wall and the side wall.   The columnar member according to any one of claims 1 to 3, wherein the low-strength portion is formed by hot stamping or partial tempering.