JP2008024019A - Bumper structure and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that in a bumper structure used for a truck etc., a long bumper member is reinforced by an reinforcement material to achieve high strength characteristics and weight reduction and stress concentration occurs easily due to offset collision etc.; and to provide a light bumper structure capable of exhibiting good high strength characteristics also with respect to offset collision and avoiding stress concentration. <P>SOLUTION: A collision assumed side reinforcement plate 21 of a reinforcement material 20 internally fitted to a long bumper member 10 is formed to have a shape along a collision assumed side inner face 11 sandwiching a bending part 15 with respect to the long bumper member 10, and a vehicle side reinforcement plate 22 at the time of mounting of the reinforcement material 20 is formed to have a shape abutting on a vehicle side inner face 12 at the time of mounting inside the bending part 15 and separated from the vehicle side inner face 12 at the time of mounting outside the bending part 15. The collision assumed side reinforcement plate 21 is connected to the vehicle side reinforcement plate 22 at the time of mounting by a connection part (connection plate 23). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bumper structure used by being attached to the front or rear of a vehicle and a method for manufacturing the same.

Bumpers used for trucks and dump trucks, for example, are required to have high strength characteristics that are unlikely to be crushed or deformed at the time of a collision in order to prevent a crashed passenger car from getting under the truck. This bumper includes what is called an underlamp protector. In recent years, the bumper has been desired to be reduced in weight in order to improve fuel consumption and athletic performance, and a hollow bumper using an aluminum alloy extruded material has been adopted in order to meet the need for this reduction in weight. The bumper 30 is attached to the stay 1 on the vehicle side, for example, as shown in FIG. Specifically, locking ridges 31, 31 that are directed inward along the longitudinal direction are formed at predetermined intervals on the inner surface of the vehicle. The locking protrusion 31 can be given a shape during extrusion molding. A nut plate 32 provided with nuts 33, 33 is inserted and locked between the locking ridges 31, 31, and the bolts 3, 3 are connected to the nut 33, sandwiching the mounting plate 2 fixed to the stay 1. The bumper 30 is fixed to the vehicle by being screwed to 33.
However, the bumper made of aluminum alloy is inferior in strength to the iron bumper, and in the event of a collision, a large load is applied particularly to the mounting portion on the vehicle side. Have been proposed (see Patent Documents 1 and 2).

The bumper reinforced with the reinforcing material will be described with reference to FIG. The long bumper material 40 made of a hollow extruded material having a rectangular cross section is provided with bent portions 41 that are bent toward the vehicle body at both ends in order to prevent hooking during traveling, and a mounting plate is provided inside the bent portion 41. 2 is attached to a stay 1 on the vehicle body side. In the long bumper member 40, a hollow reinforcing member 42 having a rectangular cross section is provided inside the bent portion 41 without any gaps, and the reinforcing member 42 covers a portion to be attached to the mounting plate 2. Has been placed. In the manufacture of the bumper, for example, a reinforcing member 42 is internally provided at a predetermined position in the long bumper 40, and a core (not shown) having a mold front surface along the bent portion 41 in the end of the long bumper 40 is provided. ) Is inserted and arranged. In this state, the bent portion 41 is formed by bending an end portion of the long bumper material 40 along the front surface of the mold. After the bending process, the core is taken out from the long bumper 40, and then fixed to the vehicle-side stay 1 with the bolt 3 and the nut 4 through the mounting plate 2.
JP 2006-1449 A JP 2003-276536 A

  However, as shown in FIG. 8, even the bumper reinforced at the vehicle side is not reinforced at the other part, particularly at the bent part, and if an impact is applied to the outer side of the bent part by offset collision or the like, a small load is applied. However, there is a problem that the bent portion easily buckles and deforms. In the bumper shown in Patent Document 1 (see FIG. 2), since it is attached and reinforced outside the bent portion, the strength against the offset collision can be increased, but the bumper has sufficient strength in the collision from the front. There is a problem of not showing.

  Furthermore, since the bumper mounting portion becomes a portion that supports the bumper when an impact is applied to the bumper, the stress transmitted through the reinforcing material when the impact is applied to the bent portion side is on the outer side of the presence or absence of the reinforcing material. There is a problem that it is easy to concentrate on the stay mounting part and the load resistance of the bumper is lowered.

  In addition, as the bumper is manufactured, the core is bent as described above. Therefore, it is necessary to insert the core into the long bumper material, place it, and remove it after bending. There is a problem of inefficiency. However, if bending is performed without using a core, a “shrunk” phenomenon occurs in which the convex surface near the bent portion is inside, and this phenomenon reduces the strength of the convex surface and decreases the strength characteristics against impact. Therefore, the use of the core is indispensable.

  The present invention has been made against the background of the above circumstances, and provides a bumper structure and a method of manufacturing the same that are lightweight, exhibit sufficient strength against frontal and offset collisions, and can be manufactured more efficiently. For the purpose.

  That is, among the bumper structures according to the present invention, the invention according to claim 1 is a bumper structure that is attached to at least one of the front and rear sides of a vehicle, and has a hollow long bumper material. The material has a bent portion that bends to the vehicle side when attached to both ends in the longitudinal direction, and a reinforcing material is provided along the longitudinal direction across the bent portion, and the reinforcing material is the long bumper material A collision assumed-side reinforcing plate along the collision assumed-side inner surface of the vehicle, and a vehicle-side mounted side that is along the vehicle-side inner surface when installed on the inner side in the longitudinal direction of the bent portion and is separated from the vehicle-side inner surface when installed on the longitudinal end side. It has a reinforcement board and the connection part which continues and connects these reinforcement boards, and is characterized by the above-mentioned.

  According to the above-described invention, when an offset collision or the like with respect to the end in the vehicle width direction occurs with respect to the bumper after being attached to the vehicle, the stress from the collision assumed surface side to the vehicle side around the bent portion of the bumper. However, the periphery of the bent portion is reinforced by a collision assumed-side reinforcing plate that is connected to and supported by the vehicle-side reinforcing plate at the time of installation, and can easily be applied with a small load against a collision outside the bent portion. High strength characteristics without deformation and buckling. The stress applied to the collision assumed surface side is transmitted from the collision assumption side reinforcing plate to the connecting portion and the vehicle side reinforcing plate at the time of attachment. The vehicle-side reinforcing plate at the time of installation is located along the inner surface of the vehicle-side at the time of installation on the inside of the bent portion, and at the end side so as to be separated from the inner surface of the vehicle-side at the time of installation. On the end side, the long bumper material is not applied to the wall surface on the vehicle side, but is transmitted to the vehicle side wall surface of the long bumper material inside the bent portion. Is prevented from being concentrated, and the load resistance of the bumper is prevented from being lowered.

  In addition, although the reinforcing material needs to have the said collision assumption side reinforcement board, the vehicle side inner surface at the time of attachment, and the connection part which supports these reinforcement boards in connection with these reinforcement boards, it is specific. The cross-sectional shape is not limited to the shape, and an appropriate shape such as a rectangular shape, a C shape, or an H shape can be selected. Further, the length of the reinforcing material in the longitudinal direction is not particularly limited as long as it extends to both sides in the longitudinal direction with at least the bent portion interposed therebetween. However, when the attachment part to the vehicle is located on the inner side in the vehicle width direction of the bent part, it is desirable that the part extends beyond the attachment part to the inside.

  The invention according to claim 2 is characterized in that the reinforcing member is in the longitudinally inner side of the bent portion, the collision assumed-side reinforcing plate is in close contact with the collision assumed-side inner surface, and the vehicle-side reinforcing plate at the time of attachment. Is closely in contact with the vehicle-side inner surface during the attachment.

  According to the above-described invention, the impact-reducing side reinforcing plate of the reinforcing material and the vehicle-side reinforcing plate at the time of attachment are in close contact with the inner surface of the long bumper material on the inner side in the longitudinal direction of the bent portion, so that impact or When subjected to deformation, the reinforcing material is reliably supported by the long bumper material, and exhibits high strength characteristics.

  The invention of a bumper structure according to claim 3 is characterized in that the reinforcing material is formed with a band-like cutout partly or entirely in the longitudinal direction along the longitudinal direction.

  According to the above-described invention, stress can be absorbed by cutting out a part of the reinforcing material, and the reinforcing material is prevented from damaging the long bumper material when stress is applied to the bumper. In particular, when bending a reinforcing material using a material stronger than the bumper material as a core, damage to the long bumper material by the reinforcing material can be minimized.

  The invention of a bumper structure according to claim 4 is characterized in that the long bumper material is made of an aluminum alloy and the reinforcing material is made of steel.

  According to the above-described invention, the long bumper material, which is a large component, is made of an aluminum alloy, so that the weight can be reduced as compared with the case where all the components are made of high-strength steel plates. In addition, the aluminum material has good formability and the mold cost is low. Furthermore, the aluminum material has good weldability and less thermal distortion due to welding. On the other hand, it is possible to reinforce the bumper with a small increase in weight by configuring the reinforcing material with strong steel only in the weakened region.

  The invention of the bumper structure according to claim 5 is characterized in that the reinforcing member is provided with a female screw portion that is screwed to a vehicle-side bolt on the vehicle-side reinforcing plate at the time of attachment.

  According to the above-described invention, a joint component separate from the long bumper material such as a nut plate and a locking portion for supporting the joint component in the long bumper material become unnecessary, and the cost can be reduced. When the locking portion is formed by extrusion, high dimensional accuracy is required, so that the material used for the long bumper material is limited to an aluminum alloy such as 6000 series having excellent extrudability. However, by eliminating the locking portion, the restriction on material selection is reduced, and it is easy to use a 7000 series aluminum alloy having high strength characteristics as a material for the long bumper material although it is relatively inferior in extrudability. Become.

  Next, the invention of the method for manufacturing a bumper structure according to claim 6 is a bumper in which a reinforcing material is housed in a hollow long bumper material having a bent portion that bends toward the vehicle side at both ends in the longitudinal direction. In the method of manufacturing a structure, the long bumper has a mold back surface along the inner surface in the longitudinal direction of the long bumper, and a mold surface matching the bending surface of the long bumper on the front surface. And inserting the core mold in which the mold back surface and the mold surface are connected by a connecting portion, bending the long bumper along the mold surface, and using the core mold as the reinforcing material, the long mold It is left in the bumper.

  According to the above-described invention, by inserting a core mold as a reinforcing material into the long bumper material before bending, a reinforcing material having an inner surface on the assumption of collision and a surface along the inner surface on the vehicle side when installed is installed. The If bending is performed in this state, the core surface of the core is along the bending surface of the long bumper material, so that the work guides work and prevents the long bumper material from shrinking. In addition, the dimensional stability of the bent shape and the angle (machining) accuracy of the bent portion are improved. After the bending process, the core mold is left as a reinforcing material, so that the punching process can be omitted and work efficiency is improved.

  As described above, the bumper structure of the present invention is a bumper structure that is attached to at least one of the front and rear sides of a vehicle, and has a hollow long bumper material, and the long bumper material has both ends in the longitudinal direction. A bent portion that bends to the vehicle side when mounted on the portion side, and is provided with a reinforcing material along the longitudinal direction across the bent portion, and the reinforcing material is the inner surface of the long bumper material on the assumed collision side A collision assumed-side reinforcing plate along the longitudinal direction of the bent portion along the vehicle-side inner surface at the time of attachment, and at the end of the longitudinal direction, the vehicle-side reinforcing plate at the time of attachment separated from the vehicle-side inner surface when installed Because it has a connecting part that supports the reinforcing plates connected to the reinforcing plate, even when stress is applied to the bent part due to offset collision etc., the reinforcing action can be reliably obtained without causing stress concentration, Light weight and high strength characteristics The effect of that bumper is obtained.

  Further, in a method of manufacturing a bumper structure in which a reinforcing material is embedded in a hollow long bumper material having a bent portion that bends to the vehicle side when attached to both ends in the longitudinal direction, the long bumper includes the It has a mold back surface along the inner surface in the longitudinal direction of the long bumper, and has a mold surface that matches the bending surface of the long bumper on the front surface, and the mold back surface and the mold surface are connected by a connecting portion. A core mold is inserted, the long bumper is bent along the mold surface, and the core mold is left as the reinforcing material in the long bumper. Bending can be performed without occurrence, and furthermore, a bumper can be efficiently manufactured without requiring a core-type extraction operation. The obtained bumper is lightweight and has excellent high strength characteristics as in the above-described invention.

Below, one Embodiment of the bumper structure of this invention is described based on FIG.
The long rectangular bumper member 10 having a rectangular cross section is made of an aluminum alloy, and preferably a 7000 series aluminum alloy (tensile strength: 250 to 420 MPa) is used. The long bumper material 10 has a length determined in accordance with the vehicle width of the vehicle to be mounted, and is preferably obtained by extrusion molding. The long bumper material 10 is provided with bent portions 15 at both ends that are bent toward the vehicle side when the vehicle is mounted. The bent portions 15 can be formed by bending or the like. Further, a reinforcing material 20 made of high-strength steel (for example, tensile strength: 590 to 1200 MPa) is provided in the long bumper material 1 with the bent portion 15 interposed therebetween.

  The reinforcing material 20 includes a collision assumed-side reinforcing plate 21 that is in close contact with the collision assumed-side inner surface 11 of the long bumper material 10 on the outer side and the inner side in the longitudinal direction of the bent portion 15, and on the inner side in the longitudinal direction of the bent portion 15. An attachment-side vehicle-side reinforcing plate 22 that is in close contact with the vehicle-side inner surface 12 when the long bumper material 1 is attached, goes straight from the bent portion 15 to the outside thereof, and gradually separates from the vehicle-side inner surface 12 toward the outside during the attachment; I have. Therefore, the distance between the collision assumed side reinforcing plate 21 and the attached vehicle side reinforcing plate 22 is gradually reduced outside the bent portion 15. Further, the assumed collision side reinforcing plate 21 and the attached vehicle side reinforcing plate 22 are connected by connecting plates 23 and 23 along inner surfaces of both side walls between the assumed bumper material 10 and the attached vehicle side. The connecting plates 23, 23 are gradually reduced in width outside the bent portion 15 in accordance with the distance between the collision assumed side reinforcing plate 21 and the vehicle side reinforcing plate 22 when attached. The reinforcing material 20 is constituted by the above-mentioned collision-side reinforcing plate 21, the vehicle-side reinforcing plate 22 and the connecting plates 23, 23, and the connecting plates 23, 23 correspond to the connecting portion of the present invention. As described above, the reinforcing member 20 is formed in a rectangular cross section, the cross-sectional area is substantially constant inside the bent portion 15, and the cross-sectional area gradually decreases from the bent portion 15 to the outside thereof.

The bumper structure configured as described above is fixed to the stays 1 and 1 provided on the vehicle on the inner side in the longitudinal direction of the bent portion 15 by bolts 3 and nuts 24 via mounting plates 2 and 2. . The nuts 24 and 24 are attached to the inner surface of the vehicle-side reinforcing plate 22 by welding or the like in advance when the reinforcing member 20 is attached before the interior of the long bumper 10 and correspond to the female screw portion referred to in the present invention. To do. By providing the nut 24 on the reinforcing member 20, the nut plate 32 used for attachment to the vehicle body and the hook 31 for holding the nut plate can be omitted. The reinforcing member 20 covers the mounting plates 2 and 2 and extends further inside.
In this embodiment, the reinforcing member 20 has a rectangular cross section, but the cross section is substantially I-shaped by providing one connecting plate as a connecting portion between the collision assumed side reinforcing plate and the vehicle side reinforcing plate at the time of attachment. What constitutes can also be used.

Next, the operation of the bumper structure will be described.
When an offset collision or the like occurs on the end of the long bumper member 10 in the longitudinal direction, the bending portion 15 is subjected to bending stress toward the vehicle side. The collision assumed side reinforcing plate 21 supported by the vehicle side reinforcing plate 22 and the connecting plate 23 is in close contact and reinforced, and is not easily deformed or buckled. At this time, since the collision assumed side reinforcing plate 21 and the vehicle side reinforcing plate 22 at the time of attachment are in close contact with the inner surface of the long bumper material 10 inside the bent portion 15, the reinforcing material 20 is reliably supported, Shows higher strength characteristics.

  In addition, the stress applied to the assumed collision side reinforcing plate 21 is transmitted to the vehicle-side reinforcing plate 22 at the time of attachment via the connecting plate 23. Since it is separated from the inner surface 12 without contact, the stress is not transmitted to the vehicle-side wall surface of the long bumper member 10 outside the bent portion 15. As a result, the stress concentration that has conventionally occurred at the stay mounting portion and the boundary between the presence and absence of the reinforcing material does not occur, and the bumper structure exhibits excellent load bearing characteristics. The vehicle-side reinforcing plate 22 at the time of mounting is firmly and firmly supported on the inner surface of the long bumper member 10 inside the bent portion 15 as described above, and has high strength characteristics against the stress. Indicates.

In the above embodiment, a reinforcing member having a rectangular cross section is used. However, a strip-shaped notch can be provided on the reinforcing plate of the reinforcing member along the bumper width direction.
The reinforcing member 25 shown in FIG. 3 is configured by a collision assumed-side reinforcing plate 26, an attached vehicle-side reinforcing plate 27, and a connecting plate 28, as in the above-described embodiment. It is the same. In this embodiment, in the assumed collision side reinforcing plate 26, a notch 29 is formed in a band shape over a part of the section along the longitudinal direction across a portion corresponding to the bent portion of the long bumper material. In the bumper structure using the reinforcing material 25, when the impact stress is applied, the notch 29 provides a stress relaxation action. Therefore, the long bumper material is caused by the stress transmitted from the reinforcing material 25 to the long bumper material. Can be prevented from being damaged. In addition, when the reinforcing material is used as a core mold as will be described later, the notch has an effect of preventing bending stress from being transmitted to the long bumper material and damaging the long bumper during bending.
In the above description, the notch is provided in a partial section of the collision assumed-side reinforcing plate. However, the notch can be provided over the entire longitudinal direction. It is also possible to provide notches in either or both.

Next, the manufacturing method of the bumper structure of this invention is demonstrated based on FIG.
First, as shown in FIG. 4 (a), a reinforcing member 20 having an outer dimension slightly smaller than the inner dimension of the long bumper material 10 is used as a core type in the long bumper material 10 made of a hollow extruded material. Insert and place. As described above, the reinforcing member 20 includes the assumed collision side reinforcing plate 21 having a flat portion along the assumed collision inner surface 11 of the long bumper material 10 and a curved surface along a bending surface to be described later. The outer surface of the collision assumed side reinforcing plate 21 is a bent surface. Further, the reinforcing member 20 has a flat vehicle-side reinforcing plate 22 that faces the collision assumed-side reinforcing plate 21 when the long bumper 10 is attached. It becomes the mold back surface along the side inner surface 12.

  After the reinforcing member 20 is positioned in advance in the long bumper material 10 at a position to be installed as a reinforcing material, a bending stress is applied to the outside of the long bumper member 10 as shown in FIG. Both ends of the bumper material 10 are bent along the curved surface of the collision assumed-side reinforcing plate 21. Accordingly, the bent bumper material 10 is formed with the bent portion 15 with high processing accuracy according to the outer surface shape of the collision assumed-side reinforcing plate 21, and the entire collision assumed-side reinforcing plate 21 is formed on the collision assumed-side inner surface 11 of the long bumper material 10. In close contact. Further, since the long bumper material 10 is deformed in accordance with the outer surface shape of the collision assumed side reinforcing plate 21 during bending, the long bumper material 10 is not contracted. By forming the bent portion 15, the vehicle-side inner surface 12 at the time of attachment is separated from the vehicle-side reinforcing plate 22 at the time of attachment from the bent portion 15 to the outside of the bent portion on the vehicle side when the long bumper material 10 is attached. Further, the vehicle-side reinforcing plate 22 at the time of attachment is in close contact with the vehicle-side inner surface 12 at the time of attachment inside the bent portion 15.

After the bending process, as shown in FIG. 4C, the reinforcing material 20 is used as a bumper structure while being left in the long bumper material 10.
The above manufacturing method does not require the design and manufacture of a dedicated core mold and does not require the action of extracting the core mold even after the bending process, so that the effects of reducing the manufacturing cost and improving the work efficiency can be obtained.

  As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to the content demonstrated by the said embodiment, In the range which does not deviate from the scope of this invention, an appropriate change is carried out. Is possible.

Next, examples of the present invention will be described in comparison with comparative examples.
In a long bumper material 10 made of JIS 7000 series aluminum alloy, a reinforcing material 20 made of steel having a thickness of 780 MPa and having a thickness of 2 mm was provided to obtain a bumper structure shown in the above embodiment. A load test assuming offset collision was performed by attaching the bumper structure to a pedestal 50 that looks like a stay and applying a load to the outside of the bent portion. For comparison, a bumper structure in which the reinforcing material 42 was provided only inside the bent portion of the long bumper material 40 was prepared, and the same load test was performed.

  In the load test, a load was continuously applied to a predetermined position on the end side of the bumper structure for a predetermined time. During the test, the load applied to the bumper structure was measured using LS-DYNA ver. Manufactured by Livermore Technology. Analysis with 970 type shows the load distribution in the collision of each part as shown in FIGS. In the figure, the black dots are displayed so as to be denser as a larger load is applied.

  As a result of the load test, in the bumper structure of the present invention, the load points are dispersed over a wide area around the bent portion, whereas in the bumper structure of the comparative example, the load points are near the outside of the mounting portion. It can be seen that stress concentration occurs.

It is sectional drawing which shows the bumper structure of one Embodiment of this invention. Similarly, it is a perspective view which shows a bumper structure. Similarly, it is a perspective view which shows the example of a change of a reinforcing material. It is a figure which shows the manufacturing process of the bumper structure of one Embodiment of this invention. It is a stress distribution figure which shows the load test result of the invention material in an Example. It is a stress distribution figure which similarly shows the load test result of a comparative example. It is sectional drawing which shows the conventional bumper structure. It is a figure which shows the other conventional bumper structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Long bumper material 11 Collision assumption side inner surface 12 At the time of attachment Vehicle side inner surface 15 Bending part 20 Reinforcement material 21 Collision assumption side reinforcement plate 22 At the time of attachment Vehicle side reinforcement plate 23 Connecting plate 25 Reinforcement material 26 Collision assumption side reinforcement plate 27 At the time of attachment Vehicle side reinforcing plate 28 Connecting plate 29 Notch

Claims (6)

  A bumper structure that is attached to at least one of the front and rear sides of a vehicle, has a hollow long bumper material, and the long bumper material has bent portions that bend to the vehicle side when attached to both ends in the longitudinal direction. A reinforcing material along the longitudinal direction with the bent portion interposed therebetween, and the reinforcing material includes a collision assumed-side reinforcing plate along an assumed collision inner surface of the long bumper material, and the bent portion. A vehicle-side reinforcing plate at the time of installation that is along the vehicle-side inner surface at the inner side in the longitudinal direction and that is separated from the inner surface of the vehicle-side at the end in the longitudinal direction, and a connecting portion that supports the reinforcing plates connected to these reinforcing plates The bumper structure characterized by having.   In the reinforcing material, on the inner side in the longitudinal direction of the bent portion, the collision assumed side reinforcing plate is in close contact with the collision assumed side inner surface, and the vehicle side reinforcing plate at the time of attachment is in close contact with the vehicle side inner surface at the time of attachment. The bumper structure according to claim 1.   3. The bumper structure according to claim 1, wherein the reinforcing material has a band-shaped notch formed partly or entirely in the longitudinal direction along the longitudinal direction. 4.   The bumper structure according to any one of claims 1 to 3, wherein the long bumper material is made of an aluminum alloy, and the reinforcing material is made of steel.   The bumper structure according to any one of claims 1 to 4, wherein the reinforcing member is provided with a female screw portion into which a vehicle-side bolt is screwed onto the vehicle-side reinforcing plate at the time of attachment.   In a method of manufacturing a bumper structure in which a reinforcing material is embedded in a hollow long bumper material having a bent portion that bends toward the vehicle side when attached to both ends in the longitudinal direction, the long bumper includes the long A core having a mold back surface along the inner surface in the longitudinal direction of the bumper, a mold surface matching the bending surface of the long bumper on the front surface, and the mold back surface and the mold surface being connected by a connecting portion A method for manufacturing a bumper structure, comprising: inserting a mold, bending the long bumper along the mold surface, and leaving the core mold as the reinforcing material in the long bumper.

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