JP2009285668A - Hollow columnar steel member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a member in which both excellent insensitivity to a collision angle and excellent shock absorbing capacity are made compatible while the member has various shapes of a thin-walled cross section. <P>SOLUTION: A hollow columnar steel member has a rectangular cross section, and torsion is formed on a part or on the whole part thereof in its longitudinal direction. The hollow columnar steel member has flanges on the outsides of the corners or on the outsides of the parts between the corners on the whole length in the longitudinal direction. When, in a cross section perpendicular to the longitudinal direction, an average length of vertical sides and lateral sides is made an average distance W[M] between ridge lines, it is preferable that the torsion is formed within the range of W[M] in the longitudinal direction from the input side of collision force and that the torsion is formed on the plurality of portions in the longitudinal direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thin hollow columnar member made of steel used as a frame member constituting a casing.

In recent years, there has been an urgent demand for cost reduction at manufacturing sites due to high fuel and high raw materials. However, the deterioration of product performance due to cost reductions may lead to the loss of manufacturer confidence. In particular, deterioration of the performance of the frame member constituting the housing must be avoided in terms of safety. In the automobile field, in order to maintain collision safety and improve fuel efficiency, there are many examples in which ultra high tension is applied to a frame member mounted on a vehicle body. That is, the cost is reduced by changing the quality of the material.
As a technique for maintaining or improving product quality and enabling cost reduction, there is a cost reduction method by changing the material itself, but development of a new material requires a long time and enormous development cost. Another possible cost reduction method is to optimize the member shape. This method is excellent in terms of development period and development cost, and various studies have been conducted in the past.
As a prior patent related to the present invention, Patent Document 1 describes a member having a twist in the longitudinal direction in an automobile energy absorbing member made of an aluminum alloy extruded member having a hollow rectangular cross section.

JP-A-9-109920

However, the internal components of the automobile are very complicated, and the collision forms of the automobile are various, so that the predicted shock absorption capability may not be exhibited. For example, in an ideal frontal collision, excellent shock absorption capability is shown, but in a collision from a slight angle, the shock absorption capability tends to decrease dramatically. Therefore, development of a member having a high impact absorbing ability even in a collision from an oblique angle to some extent, that is, a member having a high collision angle insensitivity is desired from the viewpoint of collision safety.
A member with a constricted part that induces crushing at the end of the shock absorbing member has also been developed. There is a risk that the shock absorption capacity may decrease.
From the above points, in order to improve the insensitivity of the collision angle, it does not create a weak part against the bending mode, has a deformation form that induces crushing, and has a high shock absorption capacity, so the energy absorption amount of each crushing is large It is desirable.

The member described in Patent Document 1 is considered to be a member excellent in collision angle insensitivity because it imparts a twist to a part or all of it in the longitudinal direction. However, since the member having a rectangular cross section does not have a flange portion, there is a possibility that a high shock absorption capability cannot be obtained. This is because the torsional moment is substantially proportional to the cross-sectional area perpendicular to the longitudinal direction of the member, so that the flange can improve the torsional moment, that is, the impact absorbing ability can be enhanced while having a collision angle insensitivity.
An object of the present invention is to provide a member that achieves both high impact angle insensitivity and shock absorption capability in various thin-walled cross-sectional shapes.

In order to solve the above problems, the gist of the present invention is as follows.
(1) A steel hollow columnar member having a square cross section, in which a twist is formed in a part or all of the longitudinal direction, and the flange is placed outside the corner part or outside the corner part over the entire length in the longitudinal direction. In the cross section perpendicular to the longitudinal direction, the average of the longitudinal and lateral lengths is defined as an average ridge line distance W [M], and the longitudinal force is within the range of W [M] from the input side of the impact force. A steel hollow columnar member characterized by having a twist.
(2) The steel hollow columnar member according to (1), wherein a plurality of the twists are partially present in the longitudinal direction.

  According to the present invention, it is possible to provide a member having both high impact angle insensitivity and shock absorption capability in various thin-walled cross-sectional shapes.

The best mode for carrying out the steel hollow columnar member according to the present invention will be described in detail with reference to the accompanying drawings.
First, the present invention according to (1) will be described.
In order to improve the insensitivity to the collision angle, the inventors invented to provide a torsion part to a part or all of the longitudinal direction of the steel hollow member. By adding torsion, the collision angle insensitivity can be improved by making it easier to cause a bellows-like buckling on the ridge line than in a normal rectangular cross section.
When an impact force is input from a longitudinal end to a steel hollow columnar member (hereinafter also referred to as a hollow columnar member or simply a member), deformation occurs from a weak portion in the member. If there is a weak part at the center in the longitudinal direction from the input side end (hereinafter abbreviated as the input side end), deformation is concentrated at the center and the member is bent at the center. Become. That is, in order to buckle in a bellows shape from the input side end, the input side end of the member must be easily deformed.

  Usually, as shown in FIG.2 (b), in the steel hollow columnar member which has a rectangular cross section, a deformation | transformation concentrates mainly on the ridgeline part of a member. At the start of impact force input, deformation begins to concentrate at the input side end due to the influence of deformation waves, but the ridge line portion is work hardened by tensile and compression deformation due to impact force, and the work hardened portion is the same as the deformation direction (input direction) This prevents the bellows from buckling. As a result, the center part which is not work-hardened starts to deform and bend easily.

  On the other hand, as shown in FIG. 2 (a), the twisted member is work hardened at the ridge line portion in the same manner, but the work hardened portion subjected to tensile and compressive deformation along the ridge line portion is in the deformation direction. Since it is different from (input direction), bellows-like buckling is not disturbed. Furthermore, in this case, since the work hardening is mainly due to shear deformation, it is possible to suppress a reduction in the plate thickness of the member, and thus it is possible to suppress the occurrence of extremely weak parts.

  If the twist angle per 100 mm in the longitudinal direction applied to the member is less than 1 degree, the improvement of the collision angle insensitivity is not clear. On the other hand, when the angle exceeds 60 degrees, the direction of the ridge line and the input direction of the impact force are greatly deviated, and the work hardening of the ridge line portion does not contribute to the impact absorbing ability. As a result, the impact absorption ability is greatly reduced as compared with the improvement of the collision angle insensitivity. Therefore, the lower limit of the twist angle per 100 mm is set to 1 degree, preferably 5 degrees or more, more preferably 10 degrees or more. The upper limit of the twist angle per 100 mm is 60 degrees, preferably 45 degrees or less, more preferably 30 degrees or less.

  In addition, the twisted portion is more likely to be accordion-like buckled than the untwisted portion. Therefore, it is desirable to change the location where the twisted portion is provided depending on the application. For example, when the impact force input direction is not fixed and only the impact angle insensitivity is to be increased, all the members are torsion points, and when the impact force input direction is determined to some extent, in the vicinity of the input side, for example, from the input side, For example, half of the total length may be a twisted part. If there are too few torsion parts, or if the total length of the torsion part is too small, the difference between the shock absorbing ability and the collision angle insensitivity will not be clear, as compared with a member having a simple rectangular cross section without torsion. The part is set to 1/10 or more of the entire length of the member.

  In addition, by having a flange on the outside of the corner of the steel hollow member or outside between the corner and the corner, by increasing the torsional moment necessary for buckling while twisting after impact force input, The resistance to deformation can be increased, and as a result, the shock absorbing ability can be improved. That is, in a member having a rectangular cross section without twisting, when the member buckles in a bellows shape, the member deforms in the same manner as the flange portion, and the deformation form is only simple bending, whereas the twisting as shown in FIG. When added, not only bending but also shear deformation occurs in the flange portion, so that the energy absorption amount of the flange portion can be remarkably improved. In general, we found that flanges that do not contribute much to shock absorption ability can be effectively utilized by adding torsion. Examples of cross-sectional views perpendicular to the longitudinal direction of the hollow columnar member provided with a flange are shown in FIGS.

In addition, compared to the place where the torsion was applied with the thin thin hollow columnar member made of steel and the other, the place where the torsion part is provided because the torsion part becomes weak because the input direction and the ridge line part direction are different with respect to the impact force. Is very important. For example, when a torsion part is formed only in the center part in the longitudinal direction of the member, it becomes easy to bend. In order to increase the shock absorption capability, it is desirable to repeat buckling in a bellows shape from the input side end, and therefore it is necessary to have a twisted portion at the input side end to some extent. Since the place where the most work hardening occurs is within a half wavelength from the input side end, it is desirable to have a twisted place within the half wavelength of buckling from the input side end.
That is, for example, as shown in FIG. 3, when a member having a square cross section with a side of 80 mm is buckled in a bellows shape and crushed, the twisted portion is within a distance between ridges (80 mm) which is a half wavelength of the buckling. It is desirable to have
Thus, when the shape of the rectangular cross section is a quadrangle, the distance between the ridge lines may be determined based on the average distance between the ridge lines obtained by averaging the vertical and horizontal lengths (lengths of each side).

  On the other hand, as shown in FIG. 4, a metal hollow columnar member 1 having a substantially rectangular shape having a corner portion 2 having a curvature at each of four corners and forming a closed section including the corner portion 2, In the case where one or a plurality of recesses 3 are provided on at least one side, the length of each side is the shape when the curvature is removed from the convex part 4 generated by the formation of the substantially square corner part 2 and the recess part 3. The calculation is as follows.

Referring to FIG. 5 showing between the two corners 2 in FIG. 4, that is, the convex part 4 at the end part is a straight line connecting the shoulder end point 5 to the end part 6 of the convex part. The length (Li and Lk) is the side length, and the recess 3 has a length (Lj) obtained by connecting the shoulder end points 5 of the adjacent projections 4 with a straight line and the depth of the recess, that is, the end points 5 and 7. The height Ld is the side length. In the case of a convex portion in the middle (not shown), the straight distance between the shoulder end points of the convex portion is used. In addition, when giving a curvature to the end point 5 and the end point 7, the side length of each side is calculated based on the shape when the curvature radius is set to 0 mm. The total number of sides is the total number of straight lines when the vertices (end points) are connected by straight lines. The number enclosed in <> in the figure is an example when the number of sides in a certain side is counted from the left end. In the case of FIG. 5, the number of sides is 5 for one side of a substantially square. Thus, if the remaining three sides have the same shape, the total number of sides is 20.
Therefore, the average distance between ridge lines = (4 × 80 + 8 × 10) / 20 = 20 mm (when a side of a square is 80 mm in length and has 10 mm deep recesses on four sides).

Buckling with a half-wavelength between the ridges occurs in a plane with one ridgeline on a rectangular cross section, but the wavelength is destroyed by interference with other surfaces, and it is considered that buckling occurs at an average wavelength. It is done.
Therefore, in a cross section perpendicular to the longitudinal direction, when the average of the longitudinal and lateral lengths is the average ridge line distance W [M], the twisted portion is within the range of W [M] in the longitudinal direction from the impact force input side. It is desirable to have (FIG. 3).

Next, the present invention according to (2) will be described.
As described above, the twisted portion is more likely to buckle than the untwisted portion. Therefore, it is desirable to change the longitudinal position where the twist is provided according to the application. For example, when there is a contact point with another member in the center in the longitudinal direction of the member, it may be possible that an impact force is input from a place other than the end of the shock absorbing member, for example, a contact point with another member. It is effective to provide two or more torsional portions in the longitudinal direction including the side end portions. (See Figure 6)
As an example of a member provided with a twist, FIG. 12A shows an example having a twist in the range of W [M] in the longitudinal direction from the impact force input side (invention according to (2)), and FIG. The example which has a twist in two or more places including an input side edge part, and the example which has a twist in the whole longitudinal direction (full length) in the same figure (c) are shown.

The present invention will be specifically described with reference to examples.
As an example of the present invention and a comparative example, after press-molding two plate materials having a material thickness of JSC590Y and a plate thickness of 1.4 mm into a hat type (wall height 40 mm, ceiling width 80 mm, flange length 15 mm, longitudinal direction 400 mm long), the flange portions were opposed to each other, and the butted portions were joined by spot welding to obtain a 400 mm long square pipe having a square cross section with a side length of 80 mm. Further, by twisting the hollow columnar member of this square pipe, the entire member is twisted at 0 ° (no twisting: comparative example), 30 ° (hereinafter, the present invention example), 60 °, and 90 ° per 100 mm length in the longitudinal direction. Added.

  Also, as shown in FIG. 7, using the same square pipe as described above, a portion (La) that is not twisted in the longitudinal direction from one end portion (input side end portion) is held by 30 mm, 60 mm, and 90 mm, and the remaining portion For (Lb), a member having a twisted portion of 60 ° per 100 mm length in the longitudinal direction was prepared. Since the twisting process is simply added to the square pipe, the average distance between the ridge lines is 80 mm in all cases.

  As another comparative example, after pressing two steel plates having the same material and thickness as above into a U-shape (wall height 40 mm, ceiling width 80 mm, longitudinal length 400 mm), Create a square pipe without flanges with ends joined by spot welding, and twist the entire member by twisting at 0 ° (no twisting), 30 °, 60 ° per 100 mm length in the longitudinal direction. Added.

  With respect to all the above-mentioned prepared members, the amount of energy absorbed when collapsing by 200 mm corresponding to ½ of the longitudinal direction of the member by the drop weight test was compared. In order to change the collision direction, as shown in FIG. 8, an impact due to falling weight was applied with an inclination of 0 °, 2 °, 4 °, 6 °, 8 °, and 10 ° from the major axis direction of the member. In addition, the collision direction with respect to the square pipe without a flange which is a comparative example is only a condition parallel to the major axis direction of the member, and the collision direction with respect to the square pipe having the torsion-free portion shown in FIG. Only conditions tilted 4 ° from the direction. The results are shown in FIGS. 9 and 10 and Table 1.

As shown in FIG. 9, the non-twisted member, which is a comparative example, exhibits an extremely high shock absorption capacity when the collision direction is parallel to the major axis direction of the member (impact angle 0 °). When it deviated from the major axis direction of the member, the shock absorbing ability was drastically reduced.
On the other hand, a member having a twist of 30 ° and 60 ° per 100 mm length in the longitudinal direction, which is an example of the present invention, does not greatly reduce the shock absorption capacity with respect to the deviation from the major axis direction of the member in the collision direction, and the deviation does not occur. As it became larger, it exhibited a greater ability to absorb shock than a non-twisted member. However, a member having a large torsion of 90 ° per 100 mm in the length in the longitudinal direction does not greatly reduce the shock absorption capacity against a deviation from the major axis direction of the member in the collision direction, but the overall low shock absorption capacity. Indicated.

  Moreover, as shown in FIG. 10, in the case of the member which does not have the twist which is a comparative example, a flange part hardly contributes to an impact absorption capability improvement. However, the member added with torsion, which is an example of the present invention, greatly improved the shock absorbing ability compared to the comparative example without the flange.

  Further, as an example of the present invention, in a drop weight test of a member having only 30 mm, 60 mm, and 90 mm of a non-twisted portion in the longitudinal direction from one end portion (input side end portion), only a member having a non-twisted portion of 90 mm is twisted. The bent shape was generated in the shape of the circle and the shock absorption capacity was greatly reduced. As shown in Table 1, the other members buckled in a bellows shape at the twisted portion, and a high energy absorption amount was obtained.

It is explanatory drawing which shows typically the hollow columnar member which is an example of this invention. It is explanatory drawing which shows typically the relationship between an input direction and a ridgeline direction, (a) shows the case where it has a twist, (b) shows the case where it does not have a twist, respectively. It is a graph which shows the relationship between the distance between average ridgelines, and a buckling half wavelength. It is explanatory drawing which shows typically the shape of a cross section perpendicular | vertical to the axial direction of the hollow columnar member which is an example of this invention. It is explanatory drawing which shows each side length and the number of sides in a part of cross section of FIG. It is a figure which shows an example of the twist part effective when it has a joint in the center of a hollow columnar member. It is explanatory drawing which shows typically a hollow columnar member in case there is no twist at the input end part side. It is explanatory drawing which shows typically the relationship between a collision angle and the longitudinal direction of a member. It is a graph which shows the relationship between the collision angle regarding the twist angle per 100 mm, and an energy absorption amount. It is a graph which shows the relationship between the twist angle per 100 mm regarding the presence or absence of a flange, and an energy absorption amount. It is explanatory drawing which shows typically the cross-sectional shape of the hollow columnar member which is an example of this invention, (a), (d) is the outer side between a corner part, (b), (c), ( e) shows the case where a flange is provided outside the corner portion. It is explanatory drawing which shows typically the hollow columnar member in which the twist which is an example of this invention was formed, (a) is an example which has a twist in the range of W [M] of a longitudinal direction from the input side of impact force, (B) is an example having two or more twists, and (c) is an example having twists in the entire longitudinal direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal hollow columnar member 2 Corner part 3 Recessed part 4 Convex part 5 Shoulder end point 6 End part 7 End point

Claims (2)

  It is a steel hollow columnar member having a square cross section, and a torsion is formed in a part or all of the longitudinal direction, and has a flange outside the corner part or outside the corner part over the entire length in the longitudinal direction. In the cross section perpendicular to the longitudinal direction, when the average of the longitudinal and lateral lengths is the average inter-ridge distance W [M], the twist is in the range of W [M] in the longitudinal direction from the impact force input side. A steel hollow columnar member characterized by that.   The steel hollow columnar member according to claim 1, wherein a plurality of the twists are partially present in the longitudinal direction.

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