JPH09290698A - Impact beam for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impact beam for an automobile with which infiltration of a door into a cabin can be suppressed by decreasing sectional deformation of the impact beam and increasing an impact energy absorbing amount, even when a side collision load is received, and with which load resistant performance can be adjusted without changing external shape dimension of the impact beam, and which can be manufactured by the same metal mold. SOLUTION: A high tension steel plate is press-molded, and, in both ends of a press-molded lengthwise direction, a door assembling mounting part 22 is provided, the portion between both the mounting parts 22 is press-molded, a beam part 23 is formed, it is formed into a cylindrical shape with at least one part as a plane, both end edge parts of the cylindrical shape are placed toward inward, an overlapped part 26, bent in a circular arc shape so as to place one end edge part 26a in an upper side of the other end edge part 26b, is formed, and the part 26 is mounted to face a vehicle outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is set inside a door as a safety measure for a side collision of an automobile. When the automobile undergoes a side collision, the impact beam receives a collision load to prevent the door from being deformed inside the vehicle body. The present invention relates to an impact beam for an automobile, which prevents and secures a safety space for passengers.

[0002]

2. Description of the Related Art As conventional ones of this type, for example, JP-A-4-260815 and JP-A-7-215059.
There is one as shown in FIGS. 4 and 5 described in the publication.

This is a structure in which the impact beams 10 and 10A for the vehicle are housed inside the vehicle because it is necessary to reduce the intrusion of the vehicle door to passengers when an impact load is applied from the outside in the vehicle width direction of the vehicle. It is a thing.

The impact beams 10, 10 for automobiles
A is formed to have a length extending from a substantially front end portion to a rear end portion of an automobile door, and bracket portions 11 and 11a are provided at both front and rear ends in a press-formed longitudinal direction so that the door panel is welded and fixed to the inner panel. are doing.

FIG. 4A shows this impact beam 10.
The beam portion 12 between the two bracket portions 11 is provided with a joint portion 12a whose joint surfaces are joined by welding or pressure welding. Protrusions 12b are provided along the longitudinal direction of the beam portion 12 on the inner circumference of the joint portion 12a to improve the strength of the joint portion 12a (FIG. 4).
(b)). Further, FIG. 5A shows an impact beam 10A in which the mating surfaces are joined by pressure welding without welding.

The two impact beams 10, 10A
Is attached to the door so that the joint portions 12a and 13a of the beam portions 12 and 13 are on the outer side in the vehicle width direction, and the joint portions 12a and 13a are on the compression deformation side when an impact load is applied. .

As a result, in the impact beam 10, conventionally, the insufficient strength of welding which is the joining portion 12a is dealt with by increasing the thickness of the steel sheet, but the bump portion 12b is used.
Since the welding area is widened and the welding strength is increased by the formation of the steel plate, it is not necessary to increase the plate thickness of the steel sheet, and the bending strength of the beam portion can be improved without significantly increasing the weight.

Further, in the impact beam 10A, a steel plate having a tensile strength of 140 kgf / mm ² or more is used, and it is possible to reduce the weight and cost without press-working in a pipe shape and welding the butt portion of the end. I am going to do it.

[0009]

However, in such a conventional one, since the cross section is circular, when an impact load is applied from the outside in the vehicle width direction, the beam portions 12, 13 are subjected to a load center portion. The tubular cross section is flattened and the strain increases on both the compression side and the tension side, and finally buckling occurs locally on the compression side at the center of the load, the withstand load drops sharply, and the impact load is spread over the entire impact beam. You will not be able to accept it in a distributed manner.

Therefore, the thickness of the steel plate is increased and the beam portion 1
There was a problem that the deformation and buckling of 2 and 13 had to be stopped.

However, since the current manufacturing range of the high-strength steel sheet is about 2 mm at maximum, the effect of buckling can be expected only to some extent.

Since the door is circular within the limited space inside the door, the performance of the impact beam can be improved by slightly increasing the outer diameter to increase the withstand load or decreasing the diameter to buckle. It is conceivable to increase the displacement up to to prevent the load from decreasing, but if the diameter is increased, buckling will occur early and a sudden load decrease will occur, and if the diameter is decreased, the withstand load will not increase. There was a problem, and none of the measures had a great effect, and there was also a problem that the measures would require a large amount of die modification cost and days.

Further, in the structure shown in FIGS. 4 (a) and 4 (b), since the mating surface is strongly pressed to form the raised portion 12b of the high-strength steel plate, a large residual stress remains and delayed fracture occurs on this mating surface. It is easy to occur. In addition, since the mating surface having the raised portion 12b is welded to form the beam portion, there is a problem that stress cracking due to welding is further promoted.

The steel sheets shown in FIGS. 5 (a) and 5 (b) use a steel sheet having a tensile strength of 140 kgf / mm ² or more, so that the press workability is extremely poor and the delayed fracture becomes more susceptible to delayed fracture. Has the problem of increasing the risk of causing.

Therefore, the present invention has been made by paying attention to the cross-sectional shape of the beam portion with respect to the impact load from the vehicle width direction. Even if the impact beam receives a side impact load, the cross-section deformation of the impact beam is small and the amount of impact energy absorption is small. The door can be largely suppressed from entering the vehicle interior. Another object of the present invention is to provide an impact beam for an automobile, which can be mounted in a limited space inside a door, whose load-bearing performance can be adjusted without changing the outer dimensions of the impact beam, and which can be manufactured with the same mold.

[0016]

[Means for Solving the Problems] In order to achieve the above object, the invention described in claim 1 has a tensile strength (Ts).
= 100 to 140 kgf / mm ² of high-strength steel plate is press-formed, mounting portions for door incorporation are provided at both ends of the press-molded longitudinal direction, and a beam portion is formed by press-forming between the both mounting portions. , The beam portion has a tubular shape with at least a part of a flat surface, and has an arcuate shape so that one end edge of the tubular shape faces inward and one end edge is above the other end edge. It is characterized in that a bent overlap portion is formed and the overlap portion is attached toward the outside of the vehicle.

In such a structure, both side portions of the beam portion vertically receive the side impact load of the automobile, and both end edges of the beam portion are overlapped with each other in an arc shape. Since the section modulus on the side is large, the displacement on the compression side that causes buckling is reduced and the effect of suppressing buckling is exerted, and the load is received with both end edges opened in an arc shape, so it is possible to prevent collision objects from entering. Along with this, both edges of FIG. 1 (c) move in the x and y directions, and the h dimension gradually decreases.

The amount of movement in the x and y directions is maximum at the center of the load, and the amount of movement becomes smaller as the distance from the center of the load increases, and the h dimension returns to the original dimension. That is, since both edge portions are provided in a free arc shape, the displacement caused by the intrusion of the colliding object is responsible for the deformation of the entire region near the center of the load.

Further, according to the shape of the present invention, press plate materials having different development lengths such as # 1 and # 2 can be put into the press molding die as shown in FIG. The finished pressed product can be processed with cross-sectional shapes such as # 1 and # 2 having the same h dimension and different polymerization amounts, and impact beams with different load-bearing performance such as # 1 and # 2 in Fig. 2 can be processed. Can be produced.

Therefore, the installation location of the impact beam can be secured, the required performance such as withstand load can be flexibly dealt with without modifying the press molding die, and the die modification cost does not occur even when the design is changed. You can deal without spending. Also,
Since the press-worked shape has no sharply bent portions and no welded portions and has a tensile strength of 100 to 140 kg / mm ² , the risk of causing delayed fracture or the like is extremely small. Further, since the shape can be formed only by pressing, productivity is good.

The invention described in claim 2 is the impact beam for an automobile according to claim 1, characterized in that the overlapping portion has a larger amount of polymerization as it approaches the center of the beam portion.

In such a case, when a side impact load is applied to the impact beam, since the withstand load value of the center is high, the displacement is small and the amount of intrusion into the vehicle can be suppressed small. Further, since the overlap is reduced as the distance from the center is reduced, the weight can be reduced.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

1 to 3 show an embodiment of the present invention. It should be noted that the same or equivalent parts or members as the conventional ones will be described with the same reference numerals.

First, the structure will be described with reference to FIG.
In (b) and (c), reference numeral 21 denotes an automobile impact beam, which is composed of a mounting portion 22 at both ends and a beam portion 23 between the both mounting portions 22, and the mounting portions 22 at both ends are welded to the door inner 1b. It is assembled so as to be covered by the door outer 1a and mounted on the vehicle door 1.

The automotive impact beam 21 is provided with an inner panel 1b provided with a cylindrical beam portion 23 formed by press-molding a high-tensile steel plate and a mounting portion 22 which is flattened at both ends of the beam portion 23 so as to have a substantially fan shape. Welding to

Further, as shown in FIG. 1B, the beam unit 2
No. 3 has a tubular shape in which the edge portions 26a and 26b increase in the amount of overlap toward the center to improve the load resistance of the center.

Further, as shown in the sectional view of FIG.
A flat bottom portion 24 and side portions 25 that are substantially vertical on both sides thereof
And the edge portions 26a of the side surface portions 25 are formed at appropriate height positions so that the overlapping portions 26 are formed so as to overlap each other in an arc shape toward each other. Then, when a side load from the direction of the arrow T is received, the load is applied to the overlapping portion which is a doubly overlapped arc-shaped plate material, and at the same time, one end edge portion 26a is in the x direction and the other end edge portion 26b has a structure that slides along a circular arc in the y direction.

As shown in FIG. 3, the impact beam 21 includes a steel plate serving as a beam portion 23 sandwiched between an upper die 31 and a lower die 32 and clamped by a press die.
Form 3 That is, the edge portions 26a, 26 on both side surfaces
b is overlapped in an arc shape and is slid and molded until the upper and lower dies are completely clamped. At this time, # 1 and # 2 having different developed lengths can be molded by the same mold. In the case of # 1 molding, the end edge is fully expanded to the mold surface, whereas in case of # 2 the expansion length is short and the end edge stops in the middle of the mold and press molding is completed. are doing.

The impact beam 21 for automobiles, which is press-molded by changing the expansion length by the impact beam span in this way and adjusting the polymerization amount, is welded to the inner panel 1b of the automobile door and covered with the outer panel 1a. It is installed between the two panels to prevent the door from being deformed and to secure a passenger space when the vehicle receives a side collision.

[0031]

EXAMPLE As shown in FIG. 2, as a result of a comparative test of automobile impact beams having various cross-sectional shapes, the cross-sectional shape of the present invention product has a high initial withstand load and a large displacement. Also maintains a high load and absorbs a large amount of energy.

Therefore, it was confirmed that the sectional shape of the impact beam for automobiles is appropriate.

[0033] ● trial impact beam material quality and high-tensile steel sheet: tensile strength ^{(Ts) = 125kg / mm 2} , the thickness (t) = 2.0mm specimen # 1 ... the present invention product: height (h) = 32 mm, large amount of polymerization, t = 2.0 mm # 2 ... Invention product: h = 32 mm, small amount of polymerization, t = 2.0 mm # 3 ... Conventional butt-welded pressed product: h = 32 mm, t = 2.0mm # 4 ··· Conventional product without butt welding Pressed product: h = 32mm, t = 2.0mm # 5 · · Conventional pipe product: h = 32mm, t = 2.0mm (This product only Ts = 155kg / mm ²⁾ ● load-displacement result: as shown in the test method, three-point loading system rESULTS-2 was Genwa results in load vs. displacement curves.

As a result, conventional products (# 3, # 4, # 5)
Both load capacity and energy absorption are better than the above.

[0035]

As described above, according to the first aspect of the invention, both side surfaces vertically receive a side impact load of an automobile, and both end edges are double overlapped in an arc shape. It is difficult to deform even if it receives a bump load, and the load received in an arc shape is transmitted and dispersed in the side surface direction.

Therefore, the high load resistance is high, the high load resistance is maintained even if the displacement is increased without causing partial buckling due to dispersion. There is a large difference in the amount of energy absorption between 1 and # 2 and conventional products # 3 and # 4. Further, it is shown that the energy absorption amount is larger than that of the pipe product having the tensile strength of 155 kg / mm ² shown in Sample # 5 which has been conventionally used, and the cross-sectional shape effect is exhibited. This is excellent in the effect of withstanding the side impact load and ensuring the occupant's safety space.

Also, using the same press mold, as shown in FIG.
Different characteristics can be obtained only by changing the expansion length of the beam part and making a difference in the amount of polymerization as in # 1 and # 2. Therefore, according to this molding method, it is possible to press-mold impact beams having various withstand loads with the same mold without modifying the press-molding die. Therefore, appropriate press molding can be performed according to the vehicle type, and design changes can be dealt with in a timely manner.

Further, since there is no curved surface having an acute angle and no welding is performed as a shape of press working, residual stress is small. Therefore, it is not necessary to consider age cracking even if the vehicle is used for many years.

Further, in forming the impact beam for an automobile, since it can be formed only by press bending, the productivity is good, the number of manufacturing steps can be reduced, and the cost of the impact beam can be reduced.

According to the second aspect of the present invention, since the overlap amount at the central portion of the impact beam span where the load bearing is required most is large at the central portion, the displacement is small when a side collision occurs, and the displacement is small. Intrusion can be prevented. In addition, since the amount of polymerization is reduced as the distance from the center increases, the weight can be reduced.

[Brief description of drawings]

FIG. 1A is an explanatory view showing a mounted state of an automobile impact beam of the present invention. (B) is a perspective view of an automobile impact beam showing an embodiment of the present invention. (C) is an AA enlarged sectional view of FIG. 1 (b).

FIG. 2 is a 1000-mm three-point bending load-displacement curve diagram of the impact beam for automobiles showing the same embodiment.

FIG. 3 is a press molding die of the present invention.

FIG. 4A is a perspective view of a conventional automotive impact beam (having a welded portion). FIG.
It is a BB sectional view of (a).

FIG. 5A is a perspective view of a conventional automotive impact beam (without a welded portion). 5 (b) is shown in FIG. 5 (a).
It is CC sectional drawing of.

[Explanation of symbols]

 21 ... Automotive impact beam 22 ... Mounting part 23 ... Beam part 24 ... Bottom part 25 ... Side part 26 ... Overlap part 26a ... One edge part 26b ... The other edge part

Claims (2)

[Claims] 1. A high-strength steel plate is press-formed, and both ends of the press-formed longitudinal direction are provided with mounting portions for incorporating a door,
A beam portion is formed by press-forming between the both attachment portions, and the beam portion is formed into a tubular shape having at least a part of a flat surface, and one end of the tubular shape is turned inward with one end thereof facing inward. An impact beam for an automobile, characterized in that an overlapped portion bent in an arc shape is formed so that an edge portion thereof is located above the other end edge portion, and the overlapped portion is mounted toward the outside of the vehicle. 2. The impact beam for an automobile according to claim 1, wherein the overlapping portion has a larger amount of overlapping as it approaches the center of the beam portion.