JP2010042753A - Bumper reinforcement and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bumper reinforcement having sufficient bending strength and sufficient crushing performance, and having improved performance of protecting an occupant by easing impact upon a collision accident or the like of an automobile. <P>SOLUTION: The bumper reinforcement is configured by a long cylindrical body having outward flanges on an upper surface and a bottom surface. Installation positions of the outward flanges are different in a center in a longitudinal direction and in a crash box mounting area. In the crash box mounting area, the bumper reinforcement has an opening cross-section. The crash box is installed inside the bumper reinforcement. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a bumper reinforcement for mitigating impact energy and protecting an occupant in the event of a car crash or the like, and a method for manufacturing the same.

  In recent years, there has been a demand for further improvements in passenger safety in a car crash, and crash safety standards have been raised. Under such circumstances, an increase in bending strength at the time of frontal collision or pole collision, even for bumper reinforcements that are arranged in the front or rear of the car body in the width direction of the car body, There is a need for improved transmission performance of impact loads to crash boxes and side members.

For example, in Patent Document 1 and Patent Document 2, by arranging a plate-shaped reinforcing member inside a cylindrical body forming a main body, for example, a closed cross-sectional shape of an eye shape, a Japanese character shape, or a rice field shape is formed. Having bumper reinforcement is disclosed. These bumper reinforcements have high bending strength because the reinforcing members are placed inside the cylinder, and have the function of protecting the vehicle in the event of a pole collision or an offset frontal collision, and also crash in the case of an offset diagonal collision Impact load can be effectively transmitted to the box and front side member.
Japanese Patent Laid-Open No. 9-249082 JP-A-11-059296

  However, these bumper reinforcements have a structure in which the bending strength is increased and are not easily crushed. Therefore, the bumper reinforcements cannot be sufficiently absorbed by being crushed by an impact load applied in a collision accident.

  Thus, until now, there has been no bumper reinforcement that has not only sufficient bending strength against offset frontal collision and pole collision, but also sufficient impact energy absorption performance against oblique collision.

  The present invention relates to a bumper reinforcement composed of a long cylindrical body that extends in the width direction of the vehicle body at the front or rear portion of the vehicle body, and the cylinder has a longitudinal center. The center has a closed cross-sectional shape with upper and lower surfaces, front and rear surfaces in the front-rear direction of the vehicle body, and outward flanges on the upper and lower surfaces. In addition, the crash box mounting region is configured by an open cross-sectional shape having an upper surface and a lower surface and a front surface in the front-rear direction of the vehicle body when the cylinder is disposed at the front, and when the cylinder is disposed at the rear. Consists of an open cross-sectional shape with upper and lower surfaces and a rear surface in the longitudinal direction of the vehicle body, Both areas are composed of a closed cross-sectional shape having an upper surface and a lower surface and front and rear surfaces in the front-rear direction of the vehicle body and an outward flange on the upper surface and the lower surface. The installation position of the automobile body in the front-rear direction is such that, when the cylinder is arranged at the front, the outward flange at the end in the width direction on the crash box attachment region side in a part of the region on the upper surface and the lower surface In the case where the cylinder is disposed at the rear side than the installation position in the front-rear direction of the automobile and the cylinder is arranged at the rear side, the outward direction at the end in the width direction on the crash box attachment area side in some areas The flange is located on the rear side rather than the installation position of the upper and lower surfaces of the automobile body in the front-rear direction. It is a bumper reinforcement to.

  The bumper reinforcement according to the present invention is the distance between the front surface and the rear surface from the front surface of the cylinder disposed in the front portion to the installation position in the front-rear direction of the upper surface and the lower surface of the outward flange. When H is H, it is preferably 0.0H to 0.5H at the center and 0.5H to 1.0H at the longitudinal ends of some regions.

  In the bumper reinforcement according to the present invention, the dimension from the rear surface of the cylinder disposed in the rear portion to the installation position in the front-rear direction of the upper surface and the lower surface of the outward flange is the distance between the front surface and the rear surface. When H is set, it is preferably 0.0H to 0.5H at the center and 0.5H to 1.0H at the end of some regions.

In the bumper reinforcement according to the present invention, it is desirable to further provide outward flanges on the upper surface and the lower surface in the crash box mounting region.
In these bumper reinforcements according to the present invention, it is desirable that the cylindrical body is provided by overlapping at least two constituent members.

  In these bumper reinforcements according to the present invention, the installation position in the front-rear direction on the upper surface or the lower surface of the outward flange in at least a part of the region between the center and the crash box mounting region When installed, it changes from the center toward the crash box mounting area from the front to the rear, and when the cylinder is installed at the rear, it changes from the center toward the crash box mounting area from the rear to the front. It is desirable to exist.

From another viewpoint, the present invention is constituted by a long cylindrical body having a crush box mounting area having an open cross-sectional shape on both sides of the center in the longitudinal direction, and the front or rear of the automobile body A bumper reinforcement manufacturing method provided extending in the width direction, the bumper reinforcement manufacturing method including the following first step and second step.
First step;
A first material having a width in the center in the longitudinal direction that is narrower than widths at both ends in the longitudinal direction, and a width in the center in the longitudinal direction that is wider than the widths at both ends in the longitudinal direction, as compared with the first material. Using a second material having a small size and a die in which the height of the die face surface and the height of the punch face surface change in the longitudinal direction, the hat cross-sectional heights at both ends in the longitudinal direction are in the longitudinal direction. A first intermediate material having a hat-shaped open cross-sectional shape larger than a central hat cross-sectional height, or a first intermediate material having a hat-shaped open cross-sectional shape at both ends and a flat cross-sectional shape at the center; A second intermediate material having a hat-shaped open cross-sectional shape in which the hat cross-sectional height at the center is larger than the hat cross-sectional height at both ends in the longitudinal direction, or the center has a hat-shaped open cross-sectional shape, and both ends are flat. Second intermediate element having a cross-sectional shape The step of press-forming, respectively and.
Second step;
A step of superimposing and joining the first intermediate material and the second intermediate material at respective edges.

  According to the present invention, not only a sufficient bending strength but also a sufficient crushing performance (impact energy absorption performance) is provided, so that a bumper having improved performance for mitigating impact and protecting an occupant in the event of an automobile collision accident, etc. Reinforcement can be provided.

  Hereinafter, the best mode for carrying out bumper reinforcement according to the present invention will be described in detail with reference to the accompanying drawings. In the following description, the cylinder constituting the bumper reinforcement is provided by overlapping at least two constituent members, and the outward flange existing in the cylindrical body is an overlapping portion of these at least two constituent members. Take the case of Further, in the following description, a case where the bumper reinforcement is a front bumper reinforcement attached to the front portion of the vehicle body is taken as an example.

  The bumper reinforcement according to the present embodiment is arranged at the front of the automobile body so as to extend in the width direction of the automobile body, and in the event of a car crash, etc., in order to reduce the impact and protect the occupant It is a member. The bumper reinforcement is detachably mounted at a predetermined position on the front part of the automobile body via a crash box, which is covered with, for example, a resin bumper fascia on the outer surface and fixed by appropriate means such as welding. The

  The bumper reinforcement of the present embodiment is constituted by a long cylinder. This cylindrical body has crash box attachment regions for fixing the crash box by appropriate means such as welding on both sides of the longitudinal center and at both ends in the longitudinal direction of the cylindrical body.

  The center in the longitudinal direction of the cylinder includes an upper surface and a lower surface, and a front surface (collision surface) and a rear surface (anti-collision surface) in the front-rear direction of the vehicle body orthogonal to or inclined to the upper surface and the lower surface. It has a so-called hat-shaped closed cross-sectional shape having an outward flange on the lower surface.

  In addition, the crash box mounting area has an open cross-sectional shape having an upper surface and a lower surface and a front surface in the front-rear direction of the vehicle body (unlike this embodiment, in the case of rear bumper reinforcement, the upper and lower surfaces Open sectional shape with a rear surface in the direction). It is desirable to provide outward flanges formed on the upper and lower surfaces at the end of the portion having the open cross-sectional shape. The reason why the crash box mounting region has such an open cross-sectional shape will be described later.

  Furthermore, at least a part of the region from the center to the crash box mounting region is configured by a closed cross-sectional shape including a top surface and a bottom surface and front and rear surfaces in the front-rear direction of the vehicle body and an outward flange on the top surface and the bottom surface. The It is desirable that the entire region between the center and the crash box mounting region has a closed cross-sectional shape including a front surface and a rear surface in the front-rear direction of the vehicle body and a front surface and a rear surface, and outward flanges on the upper surface and the lower surface.

  In the present embodiment, as will be described later, the cylindrical body is provided by overlapping at least two constituent members, i.e., the material on the collision surface side and the material on the anti-collision surface side. These are the overlapping portions of these at least two constituent members.

  For this reason, in the present embodiment, the outward flange is formed on both the upper surface and the lower surface of the cylindrical body, and the cylindrical body is configured only by the outer wall configured by these at least two components, and the cylindrical body No reinforcing member or the like is provided inside.

  One of the features of the bumper reinforcement of the present embodiment is that the installation position of the outward flange at the center in the longitudinal direction of the cylinder body in the front-rear direction of the automobile body on the upper surface and the lower surface is a crash box in a partial region The front flange side of the outward flange at the end in the width direction on the mounting area side than the installation position in the front-rear direction of the vehicle body on the upper surface and lower surface (the rear surface side in the case of rear bumper reinforcement unlike this embodiment) ) Is biased to exist. Therefore, this feature will be described together with the contents of the basic study conducted by the present inventors.

The present inventors use general-purpose dynamic finite element method analysis software, and a material 1 (hereinafter referred to as “hat-shaped open cross-section material”) having a hat-shaped open cross-sectional shape shown in FIG. , A plate-shaped material 2) and a hat-shaped closed cross-section member 3 (hereinafter referred to as a “hat member”) assembled by spot welding on the outward flanges 1 a and 1 b at the edges of the hat-shaped open cross-sectional material 1. (A) bending resistance performance and (b) crush performance (collision energy absorption performance) were analyzed and obtained under the conditions described below.
(A) Bending resistance performance In order to investigate the bending strength of the hat member 3, a three-point bending collision analysis was performed in the manner shown in FIG. In this analysis, assuming the bumper reinforcement, the overall length of the hat member 3 is set to 1000 mm, and a radius of 30 mm is set at a location corresponding to the crash box mounting portions 4a and 4b (positions 50 mm from both ends of the hat member 3). The rigid fulcrums 5a and 5b are arranged with a distance of 900 mm between the fulcrums 5a and 5b, and an impactor (rigid body) 6 made of a semi-cylinder having a radius of 150 mm is placed at the center in the longitudinal direction of the hat member 3 at a constant speed of 64 km / h. Collided with. This analysis model is a 1/2 symmetry model on the XY plane in consideration of symmetry.
(B) Crushing performance In order to investigate the crushing performance of the hat member 3, that is, the impact energy absorbing performance, crushing analysis was performed in the manner shown in FIG. In this analysis, like the three-point bending collision analysis shown in FIG. 2, fulcrums 5a and 5b set to a rigid body with a radius of 30 mm are arranged at locations corresponding to the crash box mounting portions 4a and 4b, and a semi-cylinder with a radius of 150 mm. The impactor (rigid body) 6 is made to collide with a portion corresponding to the crash box mounting portion 4b of the hat member 3 at a constant speed of 64 km / h.

  In this analysis, the outward flange portions 1a and 1b are spot-welded at a pitch of 25 mm in the longitudinal direction of the hat member 3, and both the hat-shaped open section material 1 and the plate-shaped material 2 are DP steel having a strength of 590 MPa class. The thickness of each plate was 1.6 mm.

  When the impactor 6 collides from the hat-shaped open section material 1 side, that is, the hat member 3 (hereinafter referred to as “forward hat section member”) in the case shown in FIGS. 2 and 3, and the impactor from the plate-shaped material 2 side. With respect to the hat member 3 (hereinafter referred to as “reverse hat cross-section member”) in the case of colliding 6, the bending resistance performance and impact energy absorption performance were investigated by the above-described three-point bending collision analysis and crush analysis.

The analysis results will be described below.
(A) Bending resistance performance FIG. 4 is a graph showing a comparison of the 1st peak load value when the impactor 6 collides with the center of the longitudinal direction of the hat member 3. From the graph of FIG. 4, the reverse hat cross-section member has a 1st peak load that is about 10% higher than that of the forward hat cross-section member, and it can be seen that the bending resistance is good. That is, the reverse hat cross-section member has excellent bending resistance because the cross-section deformation at the time of collision is small and the cross-sectional shape is easily maintained as compared with the forward hat cross-section member.
(B) Crushing performance FIG. 5 is a graph showing a comparison of absorbed energy at the time of 60 mm crushing when the impactor 6 collides with the longitudinal end of the hat member 3. As apparent from the graph of FIG. 5, the forward hat cross-section member has an absorption energy that is about 5% higher than that of the reverse hat cross-section member, indicating that the impact energy absorption performance is high.

From the results shown graphically in FIGS. 4 and 5,
(I) Compared to the reverse hat cross-section member, the forward hat cross-section member is likely to be greatly deformed at the initial stage of the collision, so the cross-sectional shape is greatly deformed and the bending strength is poor, but the impact energy absorption performance is low. And (II) the reverse hat cross-section member is higher in resistance to deformation of the cross-sectional shape at the time of collision than the forward hat cross-section member, and thus has a high bending strength, but the plate-like material 2 is bonded. Since the deformation occurs from the top of the hat-shaped open section material 1, the crash box is likely to be deformed before the bumper reinforcement is sufficiently crushed, and the impact energy absorption performance is inferior to that of the forward hat section member. It turns out that it is good.

  As understood from the above analysis results, in order to improve both the bending resistance and the collision energy absorption performance of the bumper reinforcement made of the cylinder, the upper surface of the outward flange at the center in the longitudinal direction of the cylinder and The installation position in the front-rear direction of the car body on the lower surface is more than the installation position in the front-rear direction of the car body on the upper surface and the lower surface of the outward flange at the end in the width direction on the crash box attachment region side in some areas. Changing the installation position of the outward flange in the front-rear direction on the upper or lower surface so that it is biased to the front side, specifically, at the center in the longitudinal direction of the cylinder where high bending resistance is required A reverse hat cross-sectional shape is used, and a forward hat is used in the cylindrical crash box installation area where high crushing performance is required. It is extremely effective to have a cross-sectional shape and a cross-sectional shape changing portion that continuously changes from the reverse hat cross-sectional shape to the forward hat cross-sectional shape in at least a part of the region from the center to the crush box mounting region. It is.

  That is, at the center in the longitudinal direction of the cylinder, it is desirable that the outward flange be biased to the front side, which is close to the input position of the impact load, in order to ensure high bending strength at the center, In the crash box mounting area in the longitudinal direction of the body, the outward flange is biased to the rear side, which is a position away from the input position of the impact load, in order to ensure high energy absorption performance at the crash box mounting part. Is desirable.

  From such a viewpoint, the installation position of the outward flange at the center in the longitudinal direction of the cylinder body in the front-rear direction of the automobile body on the upper surface and the lower surface is at the end in the width direction on the crash box attachment region side in a part of the region. It is desirable that the outward flange be present on the front side rather than the installation position in the front-rear direction of the automobile body on the upper surface and the lower surface.

  In this case, the distance from the front surface of the cylinder (rear surface in the case of rear bumper reinforcement) to the installation position in the front-rear direction of the upper and lower surfaces of the outward flange is the distance between the front surface and the rear surface. When H, it is 0.0H or more and 0.5H or less at the center, and is 0.5H or more and 1.0H or less at the longitudinal ends of some regions, that is, the upper surface and the lower surface of the cylindrical body In the center, the installation position of the outward flange in the center is biased to the impact surface side of the impact load of the automobile body, and in the crash box mounting region, it is biased to the side of the impact collision surface of the automobile body, Desirably, 0.0H at the center and 1.0H at the longitudinal ends of some regions, that is, a reverse hat cross-sectional shape at the center. In the region of the end portion, the forward hat cross-sectional shape is formed at the end on the end side, and in at least a part of the region between the center and the crush box mounting region, the position of the outward flange is continuous from the reverse hat cross-section to the forward hat cross-section. It is desirable to use a shape changing portion that changes to.

  In addition, when the end portion is provided with a hat-shaped open section having outward flanges formed on the upper surface and the lower surface, the dimension from the front surface of the outward flange to the installation position in the front-rear direction of the vehicle body is the distance between the front surface and the rear surface. When the distance between them is H, it is preferably 0.0H at the center and 1.0H at the end. When the length of the cylindrical body is L, it is desirable to set 0.0H in the region of at least 0.05L to -0.05L in coordinates from the center.

  FIG. 6 shows, in order from the collision end side, which is the front end side of the automobile body, the load at the time of crushing the automobile body including the bumper reinforcement, the crash box, and the front side member in which the position of the outward flange is changed as described above. It is a graph which shows an example of a relationship with a crush stroke.

  As shown in the graph of FIG. 6, the bumper reinforcement sufficiently collapses before the bumper reinforcement and crush box crush start, so that the bumper reinforcement crush stroke St1 is secured to the maximum and the absorbed energy EA1 is increased. Obtainable. Therefore, as shown in the graph of FIG. 6, after the bumper reinforcement is crushed, the crash box can be crushed by the crush stroke St2 to obtain the absorbed energy EA2, and after the crush box is crushed, the front side member is crushed. The absorbed energy EA3 can be obtained by crushing with the stroke St3.

  As described above, when the bumper reinforcement with the outward flange position changed is used as described above, when the impact load at the time of collision is applied, the bumper reinforcement is first crushed in the input direction of the impact load. Since the crushing of the crash box is started after the crushing of the reinforcement is completed, and the impact load is applied to the front side member after the crushing of the crash box is completed, it is possible to realize ideal shock energy absorption. The maximum absorbed energy (EA1 + EA2 + EA3) can be obtained for the entire automobile body, and the impact energy absorption performance of the automobile body can be maximized.

  Also, as shown in the graph of FIG. 6, when the impact energy applied is small and the impact load is less than F2, the impact energy applied only by the bumper reinforcement can be absorbed, and the crash occurs. Since the box and the front side member are not deformed, only the deformed bumper reinforcement needs to be replaced at the time of repair, and the repair cost can be reduced.

Further, another feature of the bumper reinforcement of the present embodiment is that the crash box mounting region has the above-described open cross-sectional shape, and this reason will be described.
Based on the above analysis results, the present inventors have further studied bumper reinforcement for enhancing the collision energy absorption performance by combining with a crash box. As shown in the graph of FIG. 6, the crush box has a higher crushing strength than the bumper reinforcement. Therefore, in this embodiment, the crash box is inserted and disposed inside the bumper reinforcement in order to fully exhibit the performance of the crash box from the very early stage of the collision and enhance the collision energy absorption performance. Devise the shape of the bumper reinforcement so that you can.

  Specifically, in the present embodiment, the cross-sectional shape in the crash box attachment region of the bumper reinforcement is a hat-shaped open cross-sectional shape opened to the anti-collision surface side, and the front surface (collision that constitutes this hat-shaped open cross-sectional shape is used. The front part of the crash box is directly fixed to the inner surface of the surface. By adopting such a structure, the crash box can be inserted into the inside of the hat-shaped open section of the bumper reinforcement, and the crash box can be directly attached to the collision surface. In addition, the hat-shaped open cross-sectional shape opened to the anti-collision surface side is provided with an opening large enough to insert a crash box on the anti-collision surface constituting the closed cross-sectional shape constituting the forward hat cross-sectional shape Including other shapes.

  FIG. 7 includes a crash box mounting area having a hat open cross-sectional shape opened to the anti-collision surface side in order from the collision end side, which is the front end side of the automobile body, and the crash box is inserted inside the hat open cross-section. It is a graph which shows an example of the relationship between the load and crushing stroke at the time of crushing of the automobile body provided with the bumper reinforcement, the crush box, and the front side member of the present embodiment in which a crash box is mounted on the collision surface.

  As shown in the graph of FIG. 7, when the crash box is arranged on the collision surface inside the bumper reinforcement, the crash box shown in the graph of FIG. 6 is directly fixed to the rear surface of the anti-collision surface. In comparison, since the start time of buckling deformation of the crash box is advanced and the impact load can be increased from an earlier time immediately after the start of the impact, the absorption indicated by the region surrounded by the broken line and the solid line in the graph of FIG. The collision energy can be increased by the energy α.

  Therefore, in this embodiment, the cylinder has a reverse hat cross-sectional shape at the center in the width direction where high bending performance is required, and a hat-like open cross-sectional shape opened to the anti-collision surface side in the crash box mounting region. Further, from the center to the crash box mounting region, the furan position in the cylinder and the cross-sectional shape of the cylinder are changed so that the hat-shaped open cross-sectional shape passes from the reverse hat cross-sectional shape to the forward hat cross-sectional shape.

  By having such a configuration, the bumper reinforcement of the present embodiment can have both high bending strength and excellent impact energy absorption performance in combination with a crash box.

Next, a method for manufacturing the bumper reinforcement according to the present embodiment will be described.
FIG. 8A is an explanatory view schematically showing the shape of a die die 7 used for press molding of the material on the collision surface side, and FIG. 8B is a punch metal used for press molding of the material on the collision surface side. It is explanatory drawing which shows the shape of the type | mold 8 typically, FIG.8 (c) is explanatory drawing which shows typically the shape of the die metal mold | die 9 used for the press molding of the raw material of an anti-collision surface side. 8 (d) is an explanatory view schematically showing the shape of the punch die 10 used for press-molding the material on the anti-collision surface side.

  As shown in FIGS. 8 (a) to 8 (d), die dies and punch dies are die dies whose heights of die face surfaces 7a and 9a and punch face surfaces 8a and 10a change in the longitudinal direction. Use.

  FIG. 9A is an explanatory view schematically showing a planar shape of the blank 11 used for press molding of the material on the collision surface side, and FIG. 9B is used for press molding of the material on the anti-collision surface side. It is explanatory drawing which shows the planar shape of the blank 12 typically.

  As shown in FIG. 9A, as the blank 11, the width w1 of the central portion including the center in the longitudinal direction is narrower than the width w2 of the end portions on both sides of the central portion, and also shown in FIG. 9B. A blank 11 having a longitudinal dimension L1 larger than that of the blank 12 is used. As the blank 12, a blank 12 having a width w 3 at the center including the center in the longitudinal direction is wider than the width w 4 at the end, and the dimension L 2 in the longitudinal direction is smaller than that of the blank 12 shown in FIG. .

  By using the die mold 7 shown in FIG. 8 (a) and the punch mold 8 shown in FIG. 8 (b) and pressing the blank 11 shown in FIG. And a collision surface side which is a first intermediate material having both ends having a hat-shaped open cross-sectional shape, and a shape changing portion where the position of the outward flange changes in the longitudinal direction between the center and both ends. The material can be manufactured.

  On the other hand, by using the die mold 9 shown in FIG. 8 (c) and the punch mold 10 shown in FIG. 8 (d), the blank 12 shown in FIG. A center portion having a flat cross-sectional shape, a shape changing portion in which the position of the outward flange changes in the longitudinal direction between the center portion and both ends, and the first intermediate material The material on the anti-collision surface side, which is the second intermediate material having a smaller longitudinal dimension, can be manufactured.

  FIG. 10 is an explanatory diagram showing an example of a press machine 13 that can be used for press forming of the blanks 11 and 12. Press molding of the blanks 11 and 12 can be performed by a normal method. For example, as shown in FIG. 10, a blank 11 or 12 is set on the surface of a holder 14 attached to a press machine 13, a cushion pressure is applied to the blank 11 or 12 with a die cushion 15, and the die 16 is moved downward. Thus, the blanks 11 and 12 may be press-molded. This method is a case where single-acting molding applied in a mechanical press or the like is assumed, but it is possible to perform molding similarly in a double-acting press system in which the die 16 and the punch 17 are movable.

  Subsequently, the material on the collision surface side and the material on the anti-collision surface side obtained by press molding in this way are overlapped at the respective edge portions, and the overlapped flange portions are joined by spot welding, thereby carrying out this embodiment. Bumper reinforcement in the form of can be manufactured.

  Note that the method of joining the material on the collision surface side and the material on the anti-collision surface side is not limited to the above-described spot welding, and welding such as arc welding or laser welding may be used. Mechanical bonding such as bonding may be used and is not particularly limited.

Further, before performing the press molding, the blank 11 or 12 is heated to the Ac ₃ transformation point or higher to make the metal structure of the blank 11 or 12 an austenite phase, and then the heated blank 11 or 12 is mounted on a mold. When using the so-called hot pressing method (press quenching) to obtain ultra-high-strength parts by transforming into a martensite phase by quenching by contact with the mold or cooling with a refrigerant and press forming, The strength of the material on the collision surface side and the material on the anti-collision surface side can be increased. Furthermore, it may be possible to increase the strength by combining post-heat treatment with this hot pressing method, or to perform partial quenching by, for example, induction quenching so as to increase the strength only in the central portion in the longitudinal direction. May be.

  Note that both the material on the collision surface side and the material on the anti-collision surface side are caused by the fact that the drawing depth varies in the longitudinal direction, so that the inflow of material from the flange that occurs during press molding is not constant in the longitudinal direction. As a result, wrinkles and cracks may occur in the shape change portion existing between the center portion and the end portion of the material on the collision surface side and the material on the anti-collision surface side. In order to prevent this, it is only necessary to apply a tension with a draw bead to control cracking at the end in the width direction (maximum depth) and control the inflow of material. In addition, after press molding, the flange portion of the molded member (drawn molded product) may be finished by trimming the outer diameter so as to have a predetermined length that secures an area necessary for assembling the member.

  FIG. 11A and FIG. 11B are explanatory views showing an example of a material on the collision surface side having a notch. In order to improve the moldability of the shape change part between the center of the material on the collision surface side to be manufactured or the material on the anti-collision surface side and the crash box mounting region, FIG. 11A and FIG. As shown, an appropriate number of notches 18 and 19 may be provided at appropriate positions in the shape change portion of the material on the collision surface side obtained by forming the blank 11. FIG. 11A and FIG. 11B show the material on the collision surface side, but the same applies to the material on the anti-collision surface side.

FIG. 12 is an explanatory diagram illustrating an example of the material on the collision surface side. In order to suppress the occurrence of wrinkles and cracks in the shape changing portion, the maximum depth h ₁ and the minimum depth in the shape changing portion in the material on the collision surface side obtained by forming the blank 11 shown in FIG. and h _2, and the distance _{W 1} between the position and the position of the minimum depth _{h 2} of the maximum depth _{h 1 is,} it is desirable to satisfy the relationship of _{(h 1 -h 2) / W} 1 <0.18 . Although FIG. 12 shows the material on the collision surface side, the same applies to the material on the anti-collision surface side.

  In this way, according to the present embodiment, not only a sufficient bending strength but also a sufficient crushing performance (impact energy absorption performance) is provided, so that the impact is mitigated in the event of a car crash or the like. Bumper reinforcement with enhanced performance to protect

Next, the present invention will be described more specifically with reference to examples.
Using general-purpose dynamic finite element method analysis software, bending resistance performance and crush performance (collision energy absorption performance) were examined for inventive examples 1 and 2 and comparative example 1. In the analysis, a three-point bending analysis was performed in order to analyze the bending resistance performance at the center in the longitudinal direction of the bumper reinforcement, and an oblique collision analysis was performed in order to analyze the collision energy absorption performance.

  FIG. 13 shows a state in which the crash boxes 21 and 21 are attached to the bumper reinforcement 20 of Examples 1 and 2 of the present invention, and the material 20a on the collision surface side, the material 20b on the anti-collision surface side, and the crash box 21 constituting them. It is a perspective view. FIG. 14A is a perspective view showing the shape of the bumper reinforcement 20 according to Examples 1 and 2 of the present invention. FIG. 15 is an explanatory view schematically showing the shape of the bumper reinforcement 20 of Examples 1 and 2 of the present invention, and FIG. 16 (a) is an explanatory view showing a cross section at position ± 0.29L in FIG. FIG. 16B is an explanatory view showing a cross section at the position 0L (the center in the width direction) in FIG.

  On the other hand, FIG. 17 is a perspective view showing a state in which the crash boxes 21 and 21 are attached to the bumper reinforcement 22 of Comparative Example 1, and the collision surface side material 22a, the anti-collision surface side material 22b, and the crash box 21 constituting them. It is. FIG. 14B is a perspective view showing the shape of the bumper reinforcement 22 of the first comparative example.

  In both Invention Examples 1 and 2 and Comparative Example 1, the length of the member is L = 1220 mm, and the material is a general steel with a tensile strength of 440 MPa for both the impact surface side materials 20a and 22a and the anti-collision surface side materials 20b and 22b. The plate thickness was 1.2 mm. In addition, spot welds were provided at a pitch of 30 mm in the longitudinal direction on the flange portion, which is an overlapping portion of the material 20a, 22a on the collision surface side and the material 20b, 22b on the anti-collision surface side. In addition, the length of the material 20a on the collision surface side constituting the present invention examples 1 and 2 was 1220 mm, and the length of the material 20b on the anti-collision surface side was 780 mm.

  As shown in FIGS. 13 to 16, the cross-sectional shapes of Examples 1 and 2 of the present invention are in the order of + 0.29L to + 0.32L and −0.32L to −0.29L in the coordinates from the center in the longitudinal direction. The hat cross-sectional shape is the reverse hat cross-sectional shape in the range of + 0.08L to -0.08L, and during that time (0.08L to 0.29L, -0.08L to -0.29L), the flange position is changed gently. In the range of 0.32L to 0.5L and the range of -0.5L to -0.32L, the hat-shaped open cross-sectional shape in which only the material 20a on the collision surface side is present. On the other hand, as shown in FIGS. 14B and 17, the cross-sectional shape of Comparative Example 1 is a forward hat cross-sectional shape over the entire length.

  As shown in FIG. 15, the left and right coordinates from the center in the longitudinal direction are represented by a positive value and a negative value, respectively. In addition, in any of Invention Examples 1 and 2, and Comparative Example 1, in order to adapt to the shape of the actual bumper reinforcement, as shown in FIGS. Curved.

Next, analysis conditions will be described.
(Bending resistance)
FIG. 18 is an explanatory diagram showing bending collision analysis conditions. As shown in the figure, the crash box is a cylinder having a square cross section with a side length of 70 mm and a plate thickness of 1.6 mm at a position where the distance W is 450 mm (± 0.74 L) from the center in the longitudinal direction. 21 was fixed, the anti-collision surface side was fixed, and an impactor (rigid body) 23 made of a semi-cylinder with a radius of 150 mm was made to collide with the center in the longitudinal direction of the bumper reinforcements 20 and 22 at a constant speed (15 km / h). Further, in the present invention example 2 and the comparative example 1, the total length of the crash box 21 is set to 200 mm. However, in the present invention example 1, the dimension in the vehicle front-rear direction with the crash box 21 attached is the same length as the comparative example 1. Therefore, the total length of the crash box 21 was set to 261.2 mm, which was longer than those of the inventive example 2 and the comparative example 1.
(Crush performance)
FIG. 19 is an explanatory diagram showing oblique collision analysis conditions. A crash box 21 similar to the bending collision analysis condition is attached to the bumper reinforcements 20 and 22, the anti-collision surface side is fixed, the impactor (rigid body) 24 is inclined by 10 degrees, and the bumper reinforcements 20 and 22 are covered by 40%. The bumper reinforcements 20 and 22 were made to collide with the longitudinal ends of the bumper reinforcements 20 and 22 at a constant speed (15 km / h) as indicated by the black arrows.

  Table 1 shows a comparison of the bending resistance and crushing performance at the center of the bumper reinforcements 20 and 22. In Table 1, the bending resistance performance indicates the 1st peak load value by the bending collision analysis as a ratio with Comparative Example 1 as the standard 1.0. Further, the crushing performance indicates the total absorbed energy of the bumper reinforcements 20 and 22 and the crash box 21 up to a crushing stroke of 60 mm as a ratio with the comparative example 1 as a reference 1.0.

  As shown in Table 1, Examples 1 and 2 of the present invention have a higher 1st peak load and better bending resistance than Comparative Example 1, and also have high absorbed energy and excellent impact absorption energy performance.

  From this result, the flange position is placed on the collision surface side in the center of the bumper reinforcement, placed on the anti-collision surface side inside the crash box mounting area, and the flange position is gently changed between them, and then the crash box mounting By placing the crash box into the bumper reinforcement by placing the area as an open section consisting only of the collision surface side member, it is confirmed that the bending resistance is high and the collision energy absorption performance is also high. It was.

  What is used in the description of the above embodiments is merely an example of the present invention, and the hat cross-sectional shape may have a concave portion or a convex portion in part in order to improve rigidity and strength. The dimensions, plate thickness, plate width, and material are not limited to the above-described embodiments.

  FIG. 20 is an explanatory view showing bumper reinforcements 25 to 30 according to various modified examples of the present invention, and FIGS. 20A to 20F show cross sections between B-O. In order to further improve the bending performance at the center of the bumper reinforcements 25 to 30, as shown in FIGS. 20 (a) to 20 (f), for example, the material 25a to 30a on the collision surface side between the regions B-O, The beads 31 may be provided on the materials 25b to 30b on the anti-collision surface side.

  FIG. 20A shows a bumper reinforcement 25 in which a bead 31 is provided on the material 25a on the collision surface side. FIG. 20B shows a bumper reinforcement 26 in which the shape of the beads 31 of the bumper reinforcement 25 of FIG. FIG.20 (c) shows the bumper reinforcement 27 which increased the number of the beads 31 of the bumper reinforcement 25 of Fig.20 (a).

  20 (d) to 20 (f) show bumper reinforcements 28 to 30 in which beads 31 are also provided on the materials 28b to 30b on the anti-collision surface. 20 (e) shows a bumper reinforcement 29 in which the shape of the bead 31 of the bumper reinforcement 28 of FIG. 20 (d) is changed, and FIG. 20 (f) shows the bumper reinforcement of FIG. 20 (e). The bumper reinforcement 30 which deepened the depth of 29 beads 31 is shown. A combination of these may also be used.

  Further, in the bumper reinforcement according to the present invention described in the above-described embodiments and examples, in order to further balance the center bending performance and the crushing performance of the crash box mounting region, the material on the collision surface side and the anti-collision You may make it make the hat cross-section height of each raw material of a surface side high at a center part, and may make it low at an edge part. Furthermore, in the bumper reinforcement according to the present invention, the cross-sectional shape does not need to be uniform in the longitudinal direction, and the dimensions may change in the longitudinal direction. Further, a member in which only the central material is increased in strength, a steel plate with a difference thickness, etc., the central plate thickness is increased and the plate thickness in the crash box mounting region is decreased.

The bumper reinforcement according to the present invention may be straight in the longitudinal direction or may be curved. Furthermore, it may be asymmetric in the vehicle width direction.
Further, as described above, the bumper reinforcement according to the present invention is similarly applied not only to the front bumper reinforcement but also to the rear bumper reinforcement.

  In addition, the bumper reinforcement according to the present invention does not have a material flange on the collision surface side in the open cross section of the crash box mounting region from the viewpoint of formability, crash box mounting property, and weight reduction. May be.

The crush box used in the above description is merely an example, and the shape, size, material, and the like are not limited at all.
Furthermore, in the above description, the bumper reinforcement according to the present invention is exemplified by the case where the bumper reinforcement is composed of two components. However, the present invention is not limited to such a case, and three or more configurations are possible. The same applies to the case of being constituted by members.

  21 (a) to 21 (f) show a bumper reinforcement 32 according to the present invention comprising three components: a material 32a to 37a on the collision surface side, a material 32b to 37b on the anti-collision surface side, and a reinforcement 38. It is explanatory drawing which shows -37.

  In these bumper reinforcements 32 to 37, a reinforcement 38 as a reinforcing member is disposed between AA in the longitudinal direction between the material 32a to 37a on the collision surface side and the material 32b to 37b on the anti-collision surface side. An example is shown.

  The reinforce 38 may be a flat plate as shown in FIG. 21 (a), or has beads 39 having an appropriate shape and number of installations as shown in FIGS. 21 (b) to 21 (f). It may be a thing. A combination of these may also be used. These examples are merely examples.

  Further, the bumper reinforcement according to the present invention may be joined to the crash box by spot welding, arc welding, laser welding, or mechanical joining such as bolts and rivets.

  FIG. 22 is an explanatory view schematically showing the mounting state of the bumper reinforcement 40 and the crash box 41 according to the present invention, and FIG. 22 (a) is a hat head which is a collision surface of the material 40a on the collision surface side. FIG. 22B is a rear view of the vehicle showing a situation in which the welded portion 42 is continuously welded in the front-rear direction of the vehicle body at the top portion 42, and FIG. FIG. 22C is a cross-sectional view of a hat showing a situation where continuous welding is performed, and FIG. 22C is a diagram showing a joint with a vertical wall of the hat 40a on the collision surface side by a joining means 44 such as rivet joining, spot welding or bolt fastening. It is a hat sectional view showing the situation to do.

It is explanatory drawing which shows the hat-shaped closed cross-section member used for the analysis. It is explanatory drawing which shows the point of a three-point bending collision analysis. It is explanatory drawing which shows the point of crushing analysis. It is a graph which compares and shows the 1st peak load value at the time of making an impactor collide with the center of the longitudinal direction of a hat member. It is a graph which compares and shows the absorption energy at the time of 60 mm crushing when an impactor is made to collide with the edge part of the longitudinal direction of a hat member. It is a graph which shows an example of the relationship between the load and crushing stroke at the time of crushing of an automobile body provided with bumper reinforcement, a crash box, and a front side member. It is a graph which shows an example of the relationship between the load and the crushing stroke at the time of crushing of the automobile body provided with the bumper reinforcement, the crash box, and the front side member of the embodiment. FIG. 8A is an explanatory view schematically showing the shape of a die die used for press molding of the material on the collision surface side, and FIG. 8B is a punch die used for press molding of the material on the collision surface side. FIG. 8C is an explanatory diagram schematically showing the shape of a die mold used for press molding of the material on the anti-collision surface side, and FIG. ) Is an explanatory view schematically showing the shape of a punch die used for press molding of the material on the anti-collision surface side. FIG. 9A is an explanatory view schematically showing a planar shape of a blank used for press molding of the material on the collision surface side, and FIG. 9B is a blank used for press molding of the material on the anti-collision surface side. It is explanatory drawing which shows typically the planar shape. It is explanatory drawing which shows an example of the press which can be used for press molding of a blank. FIG. 11A and FIG. 11B are explanatory views showing an example of a material on the collision surface side having a notch. It is explanatory drawing which shows an example of the raw material by the side of a collision surface. It is a perspective view which shows the state which attached the crash box to the bumper reinforcement of the example of this invention, the material of the collision surface side, anti-collision surface side material, and a crash box which comprise them. FIG. 14A is a perspective view showing the shape of the bumper reinforcement of the example of the present invention, and FIG. 14B is a perspective view showing the shape of the bumper reinforcement of the comparative example. It is explanatory drawing which shows typically the shape of the bumper reinforcement of the example of this invention. 16A is an explanatory view showing a cross section at a position ± 0.29L in FIG. 15, and FIG. 16B is an explanatory view showing a cross section at a position 0L (center in the width direction) in FIG. is there. It is a perspective view which shows the state which attached the crash box to the bumper reinforcement of the comparative example, and the collision surface side raw material, anti-collision surface side material, and crash box which comprise them. It is explanatory drawing which shows a bending collision analysis condition. It is explanatory drawing which shows diagonal collision analysis conditions. It is explanatory drawing which shows the bumper reinforcement of the various modifications of this invention. FIG. 21A to FIG. 21F are explanatory views showing the bumper reinforcement according to the present invention including three components, that is, the material on the collision surface side, the material on the anti-collision surface side, and the reinforcement. It is explanatory drawing which shows typically the bumper reinforcement which concerns on this invention, and the attachment state of a crash box, Fig.22 (a) is the front-back direction of a vehicle body in the hat top part which is a collision surface of the raw material 40a of a collision surface side FIG. 22 (b) is a hat cross-sectional view showing a situation in which welding is continuously performed in the vehicle width direction on the hat flange portion of the material on the collision surface side. Furthermore, FIG. 22 (c) is a hat cross-sectional view showing a state in which the material is joined at one point to the hat vertical wall portion of the material on the collision surface side by joining means such as rivet joining, spot welding or bolt fastening.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hat-shaped open section raw material 1a, 1b Outward flange 2 Flat cross-section raw material 3 Hat-shaped closed cross-section member 4 Crash box attaching part 5a, 5b Support point 6 Impactor (rigid body)
7 Die mold 8 Punch mold 9 Die mold 10 Punch mold 7a, 9a Die face surface 8a, 10a Punch face surface 11, 12 Blank 13 Press machine 14 Holder 14
15 Die cushion 16 Die 17 Punch 18, 19 Notch 20 Bumper reinforcement 21 according to Invention Examples 1 and 2 Crash box 20a Colliding surface side material 20b Anti-collision surface side material 22 Bumper reinforcement 22a according to Comparative Example 1 Colliding surface side Material 22b Anti-collision surface side material 23 Impactor (rigid body)
24 Impactor (rigid body)
25-30 Bumper reinforcement 25a-30a Collision surface side material 25b-30b Anti-collision surface side material 31 Bead 32-37 Bumper reinforcement 32a-37a Collision surface side material 32b-37b Anti-collision surface side material 38 Reinforce 39 Bead 40 Bumper reinforcement 41 according to the present invention Crash box 40a Collision surface side material 42 Hat top 43 Weld 44 Joining means

Claims (6)

A bumper reinforcement composed of a long cylindrical body provided extending in the width direction of the vehicle body at the front or rear of the vehicle body,
The cylindrical body has a crash box mounting region disposed on both sides of the center in the longitudinal direction,
The center includes an upper surface and a lower surface, a front surface and a rear surface in the front-rear direction of the vehicle body, and a closed cross-sectional shape including outward flanges on the upper surface and the lower surface, and the crash box mounting region includes the cylindrical body Is formed in an open cross-sectional shape having an upper surface and a lower surface and a front surface in the front-rear direction of the vehicle body, and when the cylinder is disposed in the rear portion, the upper surface, the lower surface, and the vehicle body Is composed of an open cross-sectional shape with a rear surface in the front-rear direction,
At least a part of the area between the center and the crash box mounting area is formed of a closed cross-sectional shape including an upper surface and a lower surface, and a front surface and a rear surface in the front-rear direction of the vehicle body, and an outward flange on the upper surface and the lower surface. ,
The installation position of the outward flange in the center in the front-rear direction of the automobile body on the upper surface and the lower surface is:
When the cylindrical body is disposed at the front portion, the front and rear direction of the automobile body on the upper surface and the lower surface of the outward flange at the end in the width direction on the crash box mounting region side in the partial region Than the installation position of the
When the cylindrical body is arranged at the rear portion, the outward flange of the outward flange at the end in the width direction on the crash box attachment region side in the partial region, in the front-rear direction of the automobile body on the upper surface and the lower surface Bumper reinforcement, characterized in that the bumper reinforcement is biased to the rear side of the installation position.   The dimension from the front surface of the cylindrical body arranged in the front part to the installation position of the outward flange in the front-rear direction on the upper surface and the lower surface is the distance between the front surface and the rear surface. The bumper reinforcement according to claim 1, wherein the bumper reinforcement is 0.0H to 0.5H at the center and 0.5H to 1.0H at an end in a longitudinal direction of the partial region.   The dimension from the rear surface of the cylindrical body arranged at the rear portion to the installation position of the outward flange in the front-rear direction on the upper surface and the lower surface is H as the distance between the front surface and the rear surface. 2. The bumper reinforcement according to claim 1, wherein the bumper reinforcement is 0.0H to 0.5H at the center and 0.5H to 1.0H at an end of the partial region.   The bumper reinforcement according to any one of claims 1 to 3, further comprising outward flanges on the upper surface and the lower surface in the crash box attachment region.   The bumper reinforcement according to any one of claims 1 to 4, wherein the cylindrical body is provided by overlapping at least two constituent members. A bumper reinforcement that is formed by a long cylindrical body having a crush box mounting area having an open cross-sectional shape on both sides in the center in the longitudinal direction and that extends in the width direction of the automobile body at the front or rear of the automobile body A bumper reinforcement manufacturing method comprising the following first step and second step.
First step;
A first material having a width in the center in the longitudinal direction that is narrower than widths at both ends in the longitudinal direction, and a width in the center in the longitudinal direction that is wider than the widths at both ends in the longitudinal direction, as compared with the first material. Using a second material having a small size and a die in which the height of the die face surface and the height of the punch face surface change in the longitudinal direction, the hat cross-sectional heights at both ends in the longitudinal direction are in the longitudinal direction. A first intermediate material having a hat-shaped open cross-sectional shape larger than a central hat cross-sectional height, or a first intermediate material having a hat-shaped open cross-sectional shape at both ends and a flat cross-sectional shape at the center; A second intermediate material having a hat-shaped open cross-sectional shape in which the hat cross-sectional height at the center is larger than the hat cross-sectional height at both ends in the longitudinal direction, or the center has a hat-shaped open cross-sectional shape, and both ends are flat. Second intermediate element having a cross-sectional shape The step of press-forming, respectively and.
Second step;
A step of superimposing and joining the first intermediate material and the second intermediate material at respective edges.

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