JP2008189126A - Structural member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structural member capable of being molded at high dimensional accuracy and enhancing bending impact characteristic. <P>SOLUTION: The structural member 1 is formed by working of a planar member, and is uniaxially stretched (Y axis direction in Fig.1). Further, the structural member 1 has a pair of opposed side walls 12, 12 stretching in parallel with the uniaxial direction; and a connection wall 13 stretching in parallel with the uniaxial direction and connecting the pair of side walls. In the pair of side walls 12, 12, a narrow width part a having a narrow opposed clearance and a wide width part b having the wide clearance are alternately formed in uniaxial direction. At least any one of the narrow width part a and the wide width part b exists in a plurality of portions, and the clearance is continuously uniaxially enlarged or contracted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a structural member mainly applied to an automobile body.

  In the automobile-related industry, automakers are working on strengthening and reducing the weight of automobile bodies (improving fuel efficiency) in response to social demands for improving collision safety and reducing CO2 emissions. From the viewpoint of weight reduction, low specific gravity materials such as aluminum and titanium have been put into practical use. From the viewpoint of collision safety, a material having higher strength than the conventional thin plate material is being put into practical use. In general, such an automobile member is manufactured by press molding a material.

  However, when these high-strength materials are molded by press molding, in addition to lowering the molding limit determined by cracks, “wall warp” and “Twist” occurs, and the shape (dimensions) of the molded product changes from the design value, which may cause problems when the molded products are assembled or joined (mostly by spot welding). In many cases, the high-strength material is hindered from practical use due to the balance between the dimensional accuracy of the parts and the collision strength.

  Patent Document 1 describes a hat channel type structural member for automobiles that can reduce such dimensional accuracy defects. This hat channel type structural member has one bead portion having a predetermined shape extending in the height direction of the vertical wall on each of a pair of opposing vertical walls in the elongated main body formed in a substantially U-shaped cross section. Or a plurality are formed. By forming such a bead portion, tensile stress acts in the vertical direction of the vertical wall, and the dimensional accuracy of the hat channel type structural member can be improved.

JP-A-2005-103613

However, since the hat channel type structural member described in Patent Document 1 has a structure in which a bead portion is formed at intermittent positions in the longitudinal direction of the member, the details of the structural member can be improved. Is considered difficult. That is, in Patent Document 1, it is described that it is possible to widen the range in which the above dimensional improvement effect is exhibited by installing a large number of bead portions in the longitudinal direction, but intermittently. Because of the configuration using bead portions, there is a limit to improving the dimensional accuracy to details by a method of installing a large number of the bead portions, and it is difficult to meet the demand for molding with higher dimensional accuracy.
Further, from the viewpoint of improving the collision performance, Patent Document 1 discloses that the bend-formed structural member of the hat channel type is equal to or more than the normal hat channel type structural member that does not form the bead. It is described that the characteristics of can be exhibited. However, there are few studies on the relationship between the bending impact characteristics and the bead shape, and it can be said that there is room for further improvement of the bending impact characteristics.

  In view of the above circumstances, an object of the present invention is to provide a structural member that can form a structural member with high dimensional accuracy and can improve bending impact characteristics.

Means and effects for solving the problems

  The present invention relates to a structural member mainly applied to an automobile body. And the structural member which concerns on this invention has the following some characteristics, in order to achieve the said objective. That is, the structural member of the present invention has the following features alone or in combination as appropriate.

  The first feature of the structural member according to the present invention for achieving the above object is a structural member formed by processing a plate-like member and extending in a uniaxial direction, and extending in parallel with the uniaxial direction and facing the structural member. A pair of side walls that extend parallel to the uniaxial direction and connect the pair of side walls, the pair of side walls having a narrow width portion and a wide width portion that have a wide distance. Have width variation regions alternately formed in the uniaxial direction, and in the width variation region, there are a plurality of at least one of the narrow portion and the wide portion, and the interval is the uniaxial direction. In other words, it is continuously enlarged or reduced.

According to this configuration, in the width variation region in the structural member, the side walls are formed in a convex shape or a concave shape in the direction in which the pair of side walls face each other. The moment is increased, and the occurrence of warpage can be suppressed. Also, the side wall undergoes compressive deformation and tensile deformation in the uniaxial direction, and the influence of stress due to the compression deformation and tensile deformation becomes dominant, thereby causing a stress difference between the front and back of the plate thickness that causes warpage. Can be reduced.
Furthermore, the space | interval which a pair of side wall opposes is expanded or shrunk | reduced continuously in the uniaxial direction which is a longitudinal direction of a structural member. That is, the interval is configured to continue to change in the uniaxial direction. In this case, even in a narrow range in the uniaxial direction, the side wall is formed so as to be inclined with respect to an axis parallel to the uniaxial direction. Therefore, the effect of more reliably suppressing the occurrence of warpage can be exhibited even in the narrow range. . As described above, it is possible to improve the dimensional accuracy up to the details in the entire region of the width variation region in the structural member.
In addition, the bending deformation of the structural member in which a force acts in the in-plane direction of the pair of side walls often proceeds while partly buckling the side walls. In this configuration, the shape of the side wall changes in the uniaxial direction, and the buckling is suppressed. As a result, bending deformation can be suppressed. Thereby, the bending impact characteristics can be improved.

  Further, the second feature of the structural member according to the present invention is that the narrow portion and the wide portion are each from one end to the other end of the side wall in a direction perpendicular to the uniaxial direction in the in-plane direction of the side wall. It extends to.

  According to this configuration, since the shape of the side wall changes in the uniaxial direction over the entire side wall in the width variation region, it is possible to more effectively exhibit the effect of improving the dimensional accuracy and the effect of improving the bending impact characteristics.

  A third feature of the structural member according to the present invention is that the narrow portion and the wide portion are periodically and repeatedly formed in the uniaxial direction of the width variation region.

  According to this configuration, since the shape change of the side wall in the uniaxial direction is repeated at a constant pitch, the dimensional accuracy and bending impact characteristics can be made uniform over the entire uniaxial direction in the width variation region of the structural member. . Moreover, since it is a shape which repeats periodically, shaping | molding is easy and it is possible to reduce a shaping | molding cost.

  The fourth feature of the structural member according to the present invention is that the pair of side walls are formed in a smooth curved surface in the width variation region.

  According to this configuration, it is possible to prevent stress from being concentrated on a part of the side wall, improve the bending impact characteristics, and improve the compressive strength in the uniaxial direction.

  Further, a fifth feature of the structural member according to the present invention is that a cross section of the pair of side walls by a plane parallel to the connection wall is formed in a sinusoidal shape in the width variation region. is there.

  According to this configuration, the shape can be specified by determining the values of the wavelength and the amplitude, so that the shape design of the structural member is facilitated.

  A sixth feature of the structural member according to the present invention is that a main body having a substantially U-shaped cross section perpendicular to the axial direction, and a pair of flanges extending in the uniaxial direction at both ends of the main body. It is a hat channel type member formed and configured.

  According to this structure, attachment of a structural member becomes easy by having a pair of flanges. And by the shape change of the side wall in the uniaxial direction, it becomes possible to improve the accuracy of the bending angle between the side wall and the flange formed by bending at the end of the side wall.

  A seventh feature of the structural member according to the present invention is that it is formed by drawing a plate material.

  According to this configuration, it is possible to prevent the warp due to the spring back that is likely to occur due to the drawing process, so that the rework after the molding becomes unnecessary and the productivity can be improved.

  The eighth feature of the structural member according to the present invention is that the structural member is used in a portion where a collision load acts and is subjected to bending deformation by the collision load.

  According to this structure, since the structural member has high bending strength, it is possible to suppress bending deformation that is received by a collision load. Therefore, the effect of improving the bending strength of the structural member can be used more effectively.

  A ninth feature of the structural member according to the present invention is that it is a structural member made of a thin metal plate used as a reinforcing member for an automobile body.

  According to this configuration, a material having the same Young's modulus can be used to give the bending strength necessary as a reinforcing member for an automobile without excessively increasing the plate thickness of the structural member. Can be used as Therefore, it is possible to suppress the increase in cost and increase the fuel consumption of the automobile. Moreover, since it has sufficient bending strength, it is possible to improve the safety | security at the time of a collision.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. The structural member according to the present embodiment exemplarily shows a structural member used as an automobile skeleton member (an automobile body reinforcing member).

  FIG. 1A is an overall schematic view showing a hat channel type structural member 1 according to the first embodiment of the present invention, and FIG. 1B is a structural member 1 shown in FIG. FIG. 2 is a top view (a view seen from the Z direction in FIG. 1A), and shows a shape of only the side wall 12. FIG. FIG. 1C schematically shows the shapes of the AA cross section and the BB cross section in FIG. The AA cross section is a cross section at a position where the distance between the pair of side walls 12 and 12 facing each other is the narrowest. The BB cross section is a cross section at a position where the distance between the pair of side walls 12 and 12 facing each other is the widest. 2 to 4 are schematic views showing structural members 2 to 4 according to the second to fourth embodiments. Like FIG. 1, (a) is an overall schematic view, and (b) is a top view. (C) is a sectional view. For comparison, FIG. 5 shows a hat channel type structural member 5 conventionally used as an automobile frame member.

  The structural member 1 according to the first embodiment is a structural member extending in a uniaxial direction (Y direction in FIG. 1A), and a main body having a substantially U-shaped cross section perpendicular to the axial direction. 10 and a pair of flanges 11 extending in the axial direction at both ends of the main body 10. For example, a single blank (material steel plate) having a plate thickness of about 1.4 mm is subjected to drawing processing shown in FIG. It is formed by. The main body 10 includes a pair of side walls 12 and 12 that extend in the axial direction and face each other, and a connecting wall 13 that extends in parallel with the axial direction and connects the pair of side walls 12 and 12.

  Drawing (see FIG. 6) is a processing method for a plate-like member in which the blank 16 is squeezed and formed using a punch 14 and a die 15 having substantially the same shape as the shape of the product and having a gap of about the plate thickness. FIG. 6A shows a state before processing, and FIG. 6B shows a state after processing. The blank 16 is sandwiched between the die 15 and the blank holder 17 with a predetermined pressure (see FIG. 6A), and the die 15 and the blank holder 17 are moved in the direction of the arrow in the drawing, whereby the punch 14 And the die 15 are urged and processed (see FIG. 6B).

  The pair of side walls 12 and 12 in the structural member 1 are formed to be wall surfaces that are substantially orthogonal to the connection wall 13, and a cross section of the plane parallel to the connection wall 13 is sinusoidal (hereinafter referred to as the cross section). The sine wave shape is referred to as “cross-sectional sine wave shape.” The same applies to the second to fourth embodiments. Further, the pair of side walls 12 and 12 are configured to be symmetrical with respect to a central axis extending in the longitudinal direction of the structural member 1. That is, the pair of side walls 12 and 12 are formed so that there is no phase shift in a cross-sectional sine wave shape in the longitudinal direction of the structural member 1.

  Further, as shown in FIG. 1B, when the average of the distance between one side wall and the other side wall of the pair of side walls 12 and 12 facing each other in the longitudinal direction is defined as the average distance T, the facing distance. Are narrow portions a narrower than the average interval T and wide portions b wider than the average interval T are alternately formed in the axial direction of the structural member 1. The distance between the pair of side walls 12 and 12 continuously decreases from one axial end of the structural member 1 toward the central portion in the axial direction and continues from the central portion toward the other end. Has increased. That is, the structural member 1 is configured so that the interval continuously changes in the entire axial region. In the present embodiment, the entire region in the longitudinal direction of the structural member 1 is the width variation region. Become.

  In addition, although the structural member 1 which concerns on 1st Embodiment has illustrated what consists of one narrow part a and two wide parts b, the full length of the structural member is adjusted according to a use. However, it is possible to repeatedly form the narrow portion and the wide portion.

  The structural member 1 has an overall length of 400 mm, and the pair of side walls 12 and 12 are configured to form a cross-sectional sine wave shape corresponding to one wavelength. Moreover, as shown in FIG.1 (c), the space | interval of a pair of side wall 12 * 12 is 60 mm in the part where the space | interval which opposes is the narrowest, and 80 mm in the widest part. The interval T is 70 mm. That is, the one side wall 12 is formed so that the cross-sectional sine wave shape is a sine wave shape having a wavelength of 400 mm and an amplitude of 5 mm. The height from the flange 11 at the lower end to the connecting wall 13 is 70 mm. In FIG. 1C, the portion where the plate material bends 90 degrees is formed to have an arc shape with a radius of 5 mm.

Next, the structural member 2 of the second embodiment will be described.
As shown in FIG. 2 (a), the structural member 2 of the second embodiment, like the structural member 1 of the first embodiment, is a structural member that extends in a uniaxial direction (the Y direction in FIG. 2 (a)). It is composed of a main body 20 having a substantially U-shaped cross section perpendicular to the axial direction, and a pair of flanges 21 extending in the axial direction at both ends of the main body 20, and a blank ( The steel sheet is formed by drawing. The main body 20 includes a pair of side walls 22 and 22 that extend in the axial direction and face each other, and a connecting wall 23 that extends in parallel with the axial direction and connects the pair of side walls 22 and 22. The pair of side walls 22 and 22 are formed to be wall surfaces substantially orthogonal to the connection wall 23, and are formed so that a cross section by a plane parallel to the connection wall 23 has a sinusoidal shape.

  In the structural member 2 of the second embodiment, the shape of the pair of side walls 22 and 22 is different from that of the structural member 1 of the first embodiment, and as shown in FIG. The cross-sectional sine wave shape of 22 is formed to be a sine wave shape having a wavelength of 200 mm. As in the structural member 1 of the first embodiment, the amplitude of the cross-sectional sine wave shape is 5 mm. The length of the structural member 2 is 400 mm, the distance between the pair of side walls 22 and 22 is 60 mm at the narrowest portion, 80 mm at the widest portion, and the height from the lower end flange 21 to the connecting wall 23 is 70 mm. is there.

  As described above, the structural member 2 has the widest portion b having the maximum width portion at both ends in the longitudinal direction and a wider interval than the average interval (70 mm) between the pair of side walls 22 and 22, and the average interval. The narrow portion a having a narrower interval is periodically and repeatedly formed.

  The structural member 3 of the third embodiment differs from the other embodiments in that the cross-sectional sine wave shape of the pair of side wall portions 32 and 32 has a wavelength of 100 mm. 400 mm, the distance between the pair of side walls 32 and 32 is 60 mm at the narrowest part, 80 mm at the widest part, and the height from the lower end flange 31 to the connecting wall 33 is 70 mm. It is the same.

  The structural member 4 of the fourth embodiment differs from the other embodiments in that the cross-sectional sine wave shape of the pair of side walls 42 and 42 is formed with a wavelength of 50 mm, and the amplitude is 5 mm and the total length is 400 mm. The distance between the pair of side walls 42 and 42 is 60 mm at the narrowest part, 80 mm at the widest part, and the height from the lower end flange 41 to the connecting wall 43 is 70 mm, as in the other embodiments. It is.

Next, the dimensional accuracy improvement effect of the structural members 1 to 4 according to the first to fourth embodiments will be described.
Forming analysis (FEM analysis) for forming structural members 1 to 4 and the conventional structural member 5 shown in FIG. 5 for comparison by drawing bending (hat channel draw) and investigating the influence on dimensional accuracy did. Forming analysis was performed using the material characteristic values of the 590 MPa grade steel plate shown in Table 1 for the ¼ model of the die 15, the blank holder 17, the punch 14, and the blank 16 shown in FIG. 7. Note that the die 15 and the punch 14 in FIG. 7 exemplarily illustrate the die 15 and the punch 14 for forming the conventional structural member 5 and are appropriately formed based on the shape of the structural member to be formed. The analysis was performed with the change.

  The conventional structural member 5 (see FIG. 5) used for comparison is formed as a plane in which a pair of side walls 52 and 52 are arranged in parallel to each other, and the interval between the pair of side walls 52 and 52 is the longitudinal direction ( It differs from the structural members 1 to 4 of the first to fourth embodiments in that it is constant over the entire area (Y direction in FIG. 5). However, it is the same as that of the structural members 1-4 of 1st-4th Embodiment that the average space | interval of a pair of side walls 52 * 52 is 70 mm. In addition, the overall length (400 mm), the height (70 mm) from the lower end flange 51 to the connecting wall 53, and the like are the same as those of the structural members 1 to 4.

  FIG. 8 shows the analysis result of evaluating the amount of flange jump when the molded product is taken out from the mold after molding. Specifically, in the sectional view perpendicular to the axial direction (longitudinal direction) of the structural member shown in FIG. 10 (cross-sectional view at the maximum width portion), in the height direction (Z direction in FIGS. 1 to 5) indicated by δ. It is the result of measuring the amount of displacement. The displacement amount δ is a displacement amount from the shape of the structural member at the bottom dead center (the shape indicated by the alternate long and short dash line in FIG. 10). In FIG. 8, the vertical axis is the displacement δ (mm), and the horizontal axis is the wavelength (mm) of the sinusoidal cross section of the side wall. Moreover, the evaluation result of the conventional structural member 5 is shown by a dotted line in FIG.

  FIG. 9 shows the analysis result of evaluating the warpage angle (angle indicated by θ in FIG. 10) of the side wall when the molded product is taken out from the mold after molding. In FIG. 9, the vertical axis is the warp angle θ (°), and the horizontal axis is the wavelength (mm) of the cross-sectional sinusoidal shape of the side wall. Moreover, the evaluation result of the conventional structural member 5 is shown by a dotted line in FIG.

  As shown in FIG. 8, it can be seen that the structural members 1 to 4 of the embodiment (first to fourth embodiments) of the present invention have a smaller displacement δ than the conventional structural member 5. Further, the displacement amount δ becomes smaller as the wavelength of the sinusoidal cross section becomes shorter.

  Moreover, as shown in FIG. 9, it turns out that the structural members 1-4 of embodiment (1st-4th embodiment) of this invention have a small curvature angle (theta) compared with the conventional structural member 5. As shown in FIG. Further, the warp angle θ decreases as the wavelength of the cross-sectional sine wave shape decreases.

  From the results shown in FIG. 8 and FIG. 9, it can be seen that the present invention can suppress the spring back during molding and improve the dimensional accuracy. Further, it can be seen that the smaller the wavelength of the sine wave cross section, the greater the effect of improving the dimensional accuracy.

Next, the mechanism of the dimensional accuracy improvement effect of the present invention will be described.
FIG. 11 is a diagram showing a distribution of stress (hereinafter referred to as Z-direction stress) in the press direction (Z direction in FIGS. 1 to 5) during processing on the outer surface of the side wall obtained by the above analysis. In addition, an outer surface is a surface on the opposite side to the surface where a pair of side walls oppose. Further, the Z-direction stress is the Z-direction stress of the side wall portion at the bottom dead center when the drawing is analyzed using the analysis model shown in FIG. 7, and the tensile stress is shown as positive.

  Fig.11 (a) shows the stress distribution of the outer surface in the side wall 12 of the structural member 1 which concerns on 1st Embodiment. The Z direction stress distribution is symmetrical in the longitudinal direction, and shows only the Z direction stress distribution on one end side from the longitudinal center. In addition, the Z-direction stress distribution of the central portion (a portion having a height of about 5 mm to 65 mm) excluding the bent portion connected to the connecting wall at the upper end of the side wall and the bent portion connected to the flange at the lower end is shown. Similarly, FIGS. 11B to 11D show the Z-direction stress distribution for the structural members 2 to 4 according to the second to fourth embodiments, respectively. Moreover, FIG.11 (e) has shown distribution of the Z direction stress of the conventional structural member 5 for the comparison.

  From FIG. 11, in the conventional structural member 5, the Z-direction stress acting on the side wall in the longitudinal direction (Y-axis direction in the drawing) is substantially constant, whereas the structural member according to the embodiment of the present invention. In 1-4, it turns out that the Z direction stress which acts according to the uneven | corrugated shape of a side wall is changing repeatedly in a longitudinal direction. In the structural members 1 to 4 according to the present embodiment, since the side wall continuously changes in the longitudinal direction, it is considered that compression deformation and elongation deformation are generated in the longitudinal direction during molding. The deformation in the direction is considered to have influenced the Z-direction stress. In this way, during molding, the side wall is formed in such a shape that compression or elongation deformation in the longitudinal direction occurs, and as will be described later, the Z direction in the plate thickness front and back by bending or unbending at the die shoulder portion The difference in stress can be reduced.

  12 and 13 show the stress distribution in the thickness direction of the side wall obtained by the above analysis. Similar to the stress shown in FIG. 11, the stress shown in FIGS. 12 and 13 is the Z-direction stress acting on the side wall surface and inside at the bottom dead center of the molding. The stress on the tensile side is positive and the stress on the compression side is positive. Shown as negative. In the plate thickness direction, the plate thickness center position on the side wall is 0, the surface position inside the side wall (side facing the other side wall) is -1, and the surface position outside the side wall is +1.

  FIG. 12 shows the distribution of the Z direction stress in the plate thickness direction at the position of the minimum width in the structural member and in the center in the height direction (the position indicated by the point At in FIGS. 1 to 4 and 11). FIG. 13 shows the distribution of the Z-direction stress in the plate thickness direction at the position of the maximum width in the structural member and at the center in the height direction (the position indicated by the point Bt in FIGS. 1 to 4 and 11). In the conventional structural member 5, both FIGS. 12 and 13 show the Z-direction stress distribution in the plate thickness direction at the position indicated by the point At in FIGS. 5 and 11.

  As shown in FIG. 12, the difference in the Z-direction stress between the front and back of the side wall becomes smaller as the structural member has a shorter sine wave shape in cross section. In particular, in the structural members 2 to 4 having the wavelength of 200 mm or less, the Z-direction stress is positive over the entire plate thickness direction. As described above, the Z-direction stress difference between the front and back of the side wall is reduced, so that it is possible to suppress the moment that causes the wall warp at the time of forming the hat channel. Further, as shown in FIG. 13, regarding the Z-direction stress of the portion forming the narrow portion, the structural members 3 and 4 having a short cross-sectional sine wave shape have a shorter wavelength than the conventional structural member 5. Compressive stress is dominant. Therefore, the influence of the tensile stress acting near the outer surface becomes relatively small, and the occurrence of warpage can be suppressed.

  Moreover, since the side wall of the structural members 1 to 4 according to the embodiment is formed in a convex shape or a concave shape in a direction facing the other side wall (X-axis direction), compared to a case where the side wall is formed in a planar shape. Thus, the cross-sectional secondary moment about the axis (Y-axis) parallel to the longitudinal direction in the cross-section (XY cross-section) perpendicular to the height direction (Z-axis direction) of the side wall is increased. The increase in the cross-sectional secondary moment also contributes to the suppression of the occurrence of warping as indicated by θ in FIG. 10, and is more effective.

  Next, in order to evaluate the characteristic of the structural member at the time of collision, the result of analyzing the bending collapse of the structural member (FEM analysis) will be described.

  FIG. 14 shows a three-point bending analysis model used for the analysis of bending crushing. FIG. 14A shows an overall view of the analysis model, and FIG. 14B shows a vertical cross section in the longitudinal direction of the structural member shown in FIG. As shown in FIG. 14 (a), both ends of the structural member are supported by the support portions 18 having a radius of 30 mm, and the axial central portion of the structural member is directed from the connecting wall side to the flange side (in the Z direction in the figure). In parallel), the relationship between the displacement of the pusher 19 and the load that the structural member receives from the pusher 19 when biased at a speed of 14 m / sec by the pusher 19 having a radius of 150 mm was calculated.

  The structural members to be analyzed are structural members in which the length in the longitudinal direction is 800 mm in the structural members 1 to 4 of the first to fourth embodiments and the conventional structural member 5 (length 400 mm). (The wavelength of the sinusoidal cross-sectional shape did not change). Further, the analysis was performed with the flange of the structural member fixed to a flat plate 60 extending in parallel with the connecting wall in the longitudinal direction of the structural member (see FIG. 14B). The flange and the flat plate were fixed assuming spot welding at a pitch of 50 mm in the axial direction. The mechanical properties of the steel sheet used for the analysis are as shown in Table 2.

  Further, in order to consider the influence of the biasing position of the pusher 19 in the structural member, when the widest portion of the wide portion is located at the center in the longitudinal direction of the structural member, and in the narrow portion at the center The case where the narrowest part is located was evaluated.

  Hereinafter, the structural members used in the analysis correspond to the structural members 1 to 4, and the analysis is performed by bringing the pusher 19 into contact with the wide portion, which will be referred to as structural members 1 </ b> A to 4 </ b> A. Those analyzed by being brought into contact with the narrow portion are referred to as structural members 1B to 4B. The structural member used in the analysis corresponding to the conventional structural member 5 is referred to as a structural member 5AB. FIG. 15 is an analysis model showing the load position of the pusher 19 in the structural members 1A to 4A and the structural member 5AB. FIG. 16 is an analysis model showing the load position of the pusher 19 in the structural members 1B to 4B.

  The analysis results of the above three-point bending will be described with reference to FIGS. FIG. 17 is a graph showing the relationship between the displacement of the pusher 19 and the load applied to the structural member by the pusher 19 at that time. In FIG. 16, reference numerals 1A to 4A, 1B to 4B, and 5AB denote analysis results of the structural members 1A to 4A, the structural members 1B to 4B, and the structural member 5AB, respectively.

  As shown in FIG. 17, when the displacement of the pusher 19 reaches about 5 mm, the load acting on the structural member reaches a peak. Thereafter, even if the displacement of the pusher 19 is further increased, the maximum load at the peak is not exceeded. FIG. 18 shows a bar graph obtained by extracting the maximum load at the peak for each structural member. In addition, about the conventional structural member 5AB, the maximum load at the time of a peak is shown with a dotted line. Further, as comparative examples, a structural member having the same shape as the conventional structural member 5AB and having a tensile strength of 780 MPa class (Comparative Example 1) and a structural member having a tensile strength of 980 MPa class ( The analysis results for Comparative Example 2) are also shown.

  As shown in FIG. 18, among the structural members 1 </ b> A to 4 </ b> A and the structural members 1 </ b> B to 4 </ b> B according to the embodiment of the present invention, the structural members other than the structural member 1 </ b> B are the same as the conventional structural member 5 </ b> AB. It can be seen that the maximum load is increased. It can also be seen that the maximum load increases as the wavelength of the sinusoidal cross section of the side wall of the structural member is shorter. From this, it can be seen that the strength against bending increases as the period of change in the width dimension in the axial direction of the structural member decreases. And in this embodiment, it becomes possible to increase the intensity | strength with respect to a bending irrespective of the position where force acts by making the wavelength of the cross-sectional sine wave shape of a side wall into 200 mm or less.

  In addition, when the structural members 3A and 4A having a sinusoidal cross-sectional wavelength of the side wall of 100 mm or less are compared with the structural members 3B and 4B, the structural member 3A having a load applied to the portion having the largest width dimension, It can be seen that in the structural members 3B and 4B in which the load is applied to the portion having the smallest width dimension than 4A, the load that the structural member can handle increases, that is, the strength against bending increases.

  These structural members 3A, 3B, 4A, and 4B can bear a maximum load that is greater than that of a structural member having a tensile strength of 780 MPa (Comparative Example 1), and in particular, the structural member 3B. In 4A and 4B, it is possible to take a larger maximum load than the structural member (Comparative Example 2) having a tensile strength of 980 MPa. Accordingly, in this embodiment using a material having a tensile strength of 590 MPa, the wavelength of the sine wave shape of the cross section is set to 100 mm or less, which is larger than the structural member having a tensile strength of 780 MPa (Comparative Example 1). Bending strength can be obtained, and by setting the wavelength of the sinusoidal cross-sectional shape to 50 mm or less, it is possible to obtain a bending strength greater than that of a structural member having a tensile strength of 980 MPa (Comparative Example 2). It is.

  In the structure of the structural members 1 to 4, the shape of the side wall is changed so as to form a sinusoidal shape in the longitudinal direction, and the side wall is formed in a straight line as viewed in the Z direction. Compared with the member 5, the buckling strength by the load received from a Z direction is improved. In the bending deformation of the structural member in which the force acts in the in-plane direction (Z direction) of the pair of side walls as described above, the side walls are buckled partially (particularly in the portion urged by the pusher 19). It is considered that the bending progress is suppressed as a result of improving the buckling strength, which is considered to be one cause of the increase in bending strength.

  Note that the wavelength of the sine wave shape in cross section is more prominent by setting it to be relatively smaller in relation to other dimensions (for example, the amplitude of the sine wave shape, the spacing between the pair of side walls, etc.). Can be effective. In particular, in the present embodiment, the amplitude of the sine wave shape is 5 mm, whereas the wavelength is 40 times or less of the amplitude, that is, 200 mm or less, so that the strength against bending does not depend on the position where the force acts. Can be increased.

  As described above, the structural member 1 according to the present embodiment is a structural member that is formed by processing a plate-like member and extends in a uniaxial direction (the Y-axis direction in FIG. 1A). A pair of side walls 12, 12 that extend in parallel with each other and face each other, and a connecting wall 13 that extends in parallel with the one axial direction and connects the pair of side walls 12, 12. Has a width variation region (entire region of the structural member 1) in which narrow portions a having a narrow interval and wide portions b having a large interval are alternately formed in the uniaxial direction. And a plurality of at least one of the narrow part a and the wide part b exist, and the interval is continuously enlarged or reduced in the uniaxial direction.

According to this configuration, the entire region of the structural member is configured such that the interval between the pair of side walls 12 and 12 is always changed toward the uniaxial direction, and the pair of side walls 12 and 12 face each other (FIG. 1A ) In the X-axis direction), the side wall 12 is formed in a convex shape or a concave shape. Thereby, the cross-sectional secondary moment of the side wall 12 about the axis parallel to the uniaxial direction is increased, and the occurrence of warpage can be suppressed.
Further, at the time of molding, the side wall 12 repeatedly undergoes compressive deformation and tensile deformation in the uniaxial direction, and the influence of stress due to the compression deformation and tensile deformation becomes dominant, which causes warpage. It is possible to reduce the stress difference between the front and back of the plate thickness.
Furthermore, the space | interval which a pair of side wall 12 * 12 opposes is expanded or shrunk | reduced continuously in the uniaxial direction which is a longitudinal direction of a structural member. That is, the interval is configured to continue to change in the uniaxial direction. This means that there is no portion formed in a flat plate shape extending in parallel with the uniaxial direction on the side wall. In this case, since the side wall 12 is formed to be inclined with respect to an axis parallel to the uniaxial direction even in a narrow range in the uniaxial direction, the effect of more reliably suppressing the occurrence of warpage in the narrow range is exhibited. it can. In this way, it is possible to improve the dimensional accuracy up to details in the entire region of the structural member.
Further, in the bending deformation (bending deformation shown in FIG. 14) of the structural member in which a force acts in the in-plane direction of the pair of side walls 12 and 12, it often proceeds while partially buckling the side walls. . In this configuration, the shape of the side wall is changed in the uniaxial direction, and the buckling is easily suppressed, so that bending deformation can be suppressed as a result. Thereby, the bending impact characteristics can be improved.

  Further, the narrow part a and the wide part b in the structural member 1 are respectively perpendicular to the longitudinal direction of the structural member 1 in the in-plane direction of the side walls 12 and 12 (Z direction in FIG. 1A). The side walls 12 and 12 extend from one end to the other end. Thereby, since the shape of the said side wall 12 * 12 changes in the longitudinal direction of the structural member 1 over the whole surface of the side wall 12 * 12, a dimensional accuracy improvement effect and a bending impact characteristic improvement effect can be exhibited more notably. It becomes possible.

  Further, since the pair of side walls 12 and 12 in the structural member 1 are formed in a smooth curved surface, it is possible to prevent stress from concentrating on a part of the side wall 12 and to improve the bending impact characteristics. It becomes possible to improve the compressive strength in the longitudinal direction of the member 1 for use.

  Moreover, the cross section by the surface parallel to the said connection wall 13 in a pair of side wall 12 * 12 of the structural member 1 is formed so that it may become a sine wave shape. Thereby, since a shape can be specified by determining the value of a wavelength and an amplitude, the shape design of the structural member 1 becomes easy.

  The structural member 1 includes a main body 10 having a substantially U-shaped cross section perpendicular to the uniaxial direction, and a pair of flanges 11 and 11 extending in the axial direction at both ends of the main body 10. This is a hat channel type member. According to this configuration, the structural member 1 can be easily attached by having the pair of flanges 11. And by the shape change of the side walls 12 and 12 in the uniaxial direction, it is possible to increase the accuracy of the bending angle between the side wall 12 and the flange 11 formed by bending at the end of the side wall 12.

  In addition, the structural member 1 is formed by drawing a plate material, and is formed while suppressing warpage due to a springback that is likely to be generated by drawing. Therefore, reworking after molding is unnecessary, and productivity can be improved.

  Moreover, the structural member 1 is used as a vehicle skeleton member in a portion where a collision load acts on the vehicle, and is subjected to bending deformation due to the collision load. Since the structural member 1 has high bending strength, it is possible to suppress bending deformation that is received by a collision load. Therefore, the effect of improving the bending strength of the structural member can be used more effectively. In particular, the structural members 2 to 4 having a side wall having a sinusoidal cross-sectional wavelength shorter than 200 mm have a high bending strength regardless of the position at which the impact load is received, and thus are suitable for applications that receive the bending deformation.

  The structural member 1 is a structural member made of a thin metal plate having a thickness of about 1.4 mm used as a reinforcing member for an automobile body. In this configuration, a material having the same Young's modulus can be used to provide the bending strength necessary as a reinforcing member for an automobile without excessively increasing the plate thickness of the structural member 1. Can be used as Therefore, it is possible to suppress the increase in cost and increase the fuel consumption of the automobile.

  Moreover, in the structural members 2 to 4, the narrow portion a and the wide portion b are periodically and repeatedly formed in the longitudinal direction of the structural member. Thereby, since the shape change of the side wall is repeated at a constant pitch in the longitudinal direction of the structural member, the dimensional accuracy and bending impact characteristics can be made uniform over the entire longitudinal direction in the structural member. Moreover, since it is a shape which repeats periodically, shaping | molding is easy and it is possible to reduce a shaping | molding cost.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. For example, it can be implemented with the following modifications.

(1) In the embodiment, the case where the interval continuously changes in the entire axial region of the structural member is illustrated, but FIG. 19A illustrates the upper surface of the structural member 6 according to the modification. As shown in the figure (only the side wall portion), a shape in which a pair of side walls 62 are arranged in parallel in one axial direction at both end portions in the axial direction, and there is a portion where the interval between the pair of side walls is not changed. . In the structural member 6, a region indicated by L in FIG. 19A is a width variation region.

(2) In the embodiment, the side wall is formed in a curved shape. However, as shown in FIG. 19B, a top view (only the side wall portion) of the structural member 7 according to the modification, the flat plate is partially The side wall 72 may be configured as a bent shape. Moreover, it is not restricted to forming a side wall so that the same shape may be repeated periodically in a longitudinal direction, For example, you may comprise so that different shapes may be located in a line with a predetermined pitch.

(3) In the embodiment, the narrow portion a and the wide portion b are respectively from one end of the side wall (end on the flange side) in the height direction (Z direction in FIGS. 1 to 4) of the side wall of the structural member. Although extending to the other end (end on the connection wall side), for example, as shown in FIG. 20, the structural member 8 according to the modified example, the side wall 82 is set near the end on the connection wall side (in the figure, h1). It is also possible to form a flat plate extending in the longitudinal direction at the position shown, and to form a narrow part and a wide part at a part in the height direction (position shown as h2 in the figure).

(4) The structural member is not limited to the hat channel type, and may have a configuration in which a flange is not formed at the end of the side wall.

(5) It is not limited to the structural member used as an automobile part, but can be used for various applications as a member having a structure requiring high dimensional accuracy and bending strength.

It is the schematic which shows the structural member of the hat channel type | mold which concerns on 1st Embodiment of this invention. It is the schematic which shows the structural member of the hat channel type | mold which concerns on 2nd Embodiment of this invention. It is the schematic which shows the structural member of the hat channel type | mold which concerns on 3rd Embodiment of this invention. It is the schematic which shows the structural member of the hat channel type | mold which concerns on 4th Embodiment of this invention. It is the schematic which shows the conventional structural member of a hat channel type. It is a figure for demonstrating the outline | summary of a drawing process. It is a figure which shows the model for shaping | molding analysis of drawing. It is a figure which shows the analysis result which evaluated the amount of flange splashes. It is a figure which shows the analysis result which evaluated the curvature angle of the side wall. It is a figure which shows displacement amount (delta) and curvature angle (theta) evaluated by dimensional accuracy analysis. It is a figure which shows distribution of the Z direction stress in the outer surface of a side wall. It is a figure which shows distribution of the Z direction stress in a plate | board thickness direction. It is a figure which shows distribution of the Z direction stress in a plate | board thickness direction. It is a figure which shows the model for analysis of bending crushing. It is a figure which shows the load position of the pusher in a bending crushing analysis. It is a figure which shows the load position of the pusher in a bending crushing analysis. It is a figure which shows the analysis result of a bending crush analysis. It is a figure which shows the analysis result of a bending crush analysis. It is a figure which shows the structural member which concerns on a modification. It is a figure which shows the structural member which concerns on a modification.

Explanation of symbols

1-4, 1A-4A, 1B-4B Structural member 5, 5AB Conventional structural member 10 Main body 11 Flange 12 Side wall 13 Connection wall a Narrow part b Wide part

Claims (9)

A structural member formed by processing a plate-like member and extending in a uniaxial direction,
A pair of side walls extending parallel to the uniaxial direction and facing each other;
A connecting wall that extends parallel to the uniaxial direction and connects the pair of side walls;
The pair of side walls have a width variation region in which a narrow portion having a narrow interval and a wide portion having a wide interval are alternately formed in the uniaxial direction,
In the width variation region, at least one of the narrow portion and the wide portion is present in plural, and the interval is continuously expanded or contracted in the uniaxial direction. Element.   2. The structure according to claim 1, wherein each of the narrow portion and the wide portion extends from one end of the side wall to the other end in a direction perpendicular to the uniaxial direction in the in-plane direction of the side wall. Materials.   The structural member according to claim 1, wherein the narrow portion and the wide portion are periodically and repeatedly formed in the uniaxial direction of the width variation region.   The structural member according to claim 1, wherein the pair of side walls are formed in a smooth curved surface in the width variation region.   The structural member according to claim 4, wherein a cross section of the pair of side walls by a plane parallel to the connection wall is formed in a sinusoidal shape in the width variation region.   A hat channel type member configured by forming a main body having a substantially U-shaped cross section perpendicular to the axial direction and a pair of flanges extending in the uniaxial direction at both ends of the main body. The structural member according to at least one of claims 1 to 5.   The structural member according to claim 1, wherein the structural member is formed by drawing a plate material.   The structural member according to claim 1, wherein the structural member is used in a portion on which a collision load acts and is subjected to bending deformation by the collision load.   The structural member according to claim 8, which is a structural member made of a thin metal plate used as a reinforcing member for an automobile body.

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