JPH07100184B2 - Manufacturing method of automobile door guard bar - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a method for manufacturing a door guard bar for improving the strength of an automobile door against side collision of a vehicle.

2. Description of the Related Art Examples of this type of conventional technology include, for example, FIGS.
There is something like the one shown in the figure. The automobile door 1 is mainly formed by an outer panel 2 and an inner panel 3, and a door guard bar 4 is provided in a space A formed by the both panels 2 and 3 as shown in FIGS. 12 and 13. It is arranged along the vehicle front-rear direction.

The door guard bar 4 is provided mainly for reinforcement against crushing of the door 1 at the time of a side collision of a vehicle, etc., and is composed of a guard bar main body 5 and a reinforcement 6 as shown in FIG. There is. This guard bar body 5
Is assembled by spot welding the intermediate portion 5a and the front and rear end portions 5b, 5c which are divided into three parts, and further, the reinforcement 6 is spot-welded to the guard bar main body 5, so that FIG. The door guard bar 4 is assembled as shown in. The front and rear end portions 5b and 5c of the door guard bar 4 are fixedly arranged on the inner panel 3 of the door 1.

Incidentally, as this kind of thing, for example, the actual exploitation Sho 57-168414
There is one such as that described in the publication.

Problems to be Solved by the Invention However, since such a door guard bar 4 is composed of a total of four parts, in order to manufacture this door guard bar 4, the four parts are each formed by press molding. In order to increase the number of pressing steps, and to weld separated parts to each other, these parts must be positioned, and as a result, a positioning device is required. The door guard bar 4 is difficult to manufacture. Furthermore, since it is a normal steel plate, it is necessary to secure a plate thickness in order to secure strength, which causes an increase in weight,
There is a problem.

Means for Solving the Problems In order to solve the problems, according to the present invention, a plurality of main beads along the longitudinal direction are formed side by side on a substantially rectangular guard bar body made of one high-tensile steel plate. Is
A method of manufacturing a door guard bar, which is installed in a door in a vehicle front-rear direction to reinforce an automobile door, wherein a first drawing of the first main bead from a product size state is performed by first drawing the plurality of main beads. When forming a second main bead adjacent to the first main bead by a subsequent drawing process with a large cross-sectional area and an R shape, the first main bead is corrected to a product state and reduced, One of the features of the method is a method of manufacturing a door guard bar for an automobile, which is formed by supplying a surplus material due to the reduction of one main bead to the second main bead.

Action According to such means, the first main bead is formed in the first drawing step to have a larger cross-sectional area and R shape than the product state,
When the second main bead adjacent to the first main bead is drawn, the surplus material is supplied to the second main bead side by correcting the first main bead to the product size and reducing the size. ing. In the case of this supply, the material becomes easy to flow by forming the R shape large. As a result, even when this second main bead is formed, a good product door guard bar can be obtained without causing cracks or the like due to insufficient material. Since this door guard bar is integrally molded, it is easy to manufacture, and since it uses a high-tensile steel plate, it can be made lightweight and secure its strength.

EXAMPLES Hereinafter, the present invention will be described based on examples.

1 to 11 are views showing an embodiment of the present invention.

First, the structure of the door guard bar 11 will be described.

As shown in FIGS. 1 to 3, the door guard bar 11 is formed of a single high-tensile steel plate, and the high-tensile steel plate having a tensile strength of 80 kg / mm ² or more is used. To be done. In this door guard bar 11, a guard bar body 12 is formed in a substantially rectangular shape, and both end portions of the body 12 are
There are 3 main beads 13,14,15 along the longitudinal direction between 12a.
Books are juxtaposed. The size of this guard bar body 12 is
The length l is about 1000 mm and the width b is about 180 mm. Further, both end portions 12a are attachment portions to a door panel (not shown). Further, the guard bar main body 12 has a total length in a direction substantially orthogonal to the main beads 13, 14, 15.
Ten sub beads 16 ... Are formed. For details, the sub-beads 16 ...
Moreover, they are formed near both ends 12a and in the center.

Next, an embodiment of the method of manufacturing the door guard bar 11 according to the present invention will be described.

First, the guard bar main body 12 formed in a rectangular shape is
As shown in the figure, in the first drawing (drawing) step, the central main bead 13 as the first main bead is formed by drawing.

The first draw mold 17 for performing this molding has a structure as shown in FIG. That is, reference numeral 18 in the drawing is the upper plate,
Reference numeral 19 denotes a lower mold plate, and a die 20 having one bead forming recess 20a formed therein is fixed to the upper mold plate 18, while the lower mold plate 19 is inserted into the bead forming recess 20a. One punch 21 is fixed. Further, a blank holder 22 (wrinkle suppressing member) for sandwiching a blank (guard bar main body 12) with the die 20 is provided via a cushion pin 23.

Guard bar body 12 which is a high-strength steel plate during press forming
Is placed on the blank holder 22 and the die 20 is lowered, whereby the punch 21 is inserted into the bead forming recess 20a, and the central main bead 13 is formed (see FIG. 4). At this time, since the blank holder 22 is pushed as the die 20 descends, the holder 22 descends via the cushion pin 23.

In this case, the cross-sectional shape of the main bead 13 at the center is larger than the cross-sectional shape in the product state shown by the solid line in FIG. 2 as shown by the chain double-dashed line in the figure.

Next, in a second drawing (drawing) step, main beads 14 and 15 on both sides as second main beads adjacent to the central main bead 13 are formed by drawing (see FIG. 5).

The second draw mold 24 for performing this molding has a structure as shown in FIG. In other words, reference numeral 25 in the figure is the upper mold plate,
26 is a lower mold plate, and a die 27 having three bead forming recesses 27a is fixed to the upper mold plate 25,
Further, three punches 28 to be inserted into the bead forming recesses 27a are fixed to the lower mold plate 26. Further, a blank holder 29 is arranged via a cushion pin 30.

At the time of press molding, each punch 28 has a bead forming recess 27
Inserted into a, main beads 14 and 15 on both sides and a main bead 13 at the center are formed.

At this time, the main beads 14 and 15 on both sides are formed into a substantially product-shaped cross-sectional shape. On the other hand, the main bead 13 in the center is
In the first drawing step, a cross-sectional area larger than the cross section in the product state and an R shape are formed, and this is corrected by the second draw die 24 into a substantially cross-sectional shape in the product state and reduced. Then, the reduced amount of material will be the main beads 14,1 on both sides.
It is supplied by flowing to the 5 side. This flow is favorably performed by increasing the R shape.

If the material on the side of the main bead 13 in the center is made to flow to the side of the main beads 14 and 15 on both sides in this way, cracks may occur in the beads 14 and 15 when molding the main beads 14 and 15 on both sides. Absent.

Next, in a re-strike process as shown in FIG. 6, the product formed into the substantially product shape as described above is formed into a regular product state. At the same time, the sub-bead 16 is formed at the position as described above to prevent the door guard bar 11 from twisting.

That is, the high-strength steel plate is press-formed and the main beads 1
The formation of 3,14,15 causes a larger compressive residual stress than ordinary steel plates. According to the experimental data as shown in Fig. 11, this stress is measured at the parts A, B, C, D, E, F in Fig. 10, and the compressive stress in the principal stress direction is shown by the line I in Fig. 11. Further, the stress in the direction of 90 ° to the principal stress direction has a value as shown by the line in the figure. Looking at this, in particular, the stress is large at the portion E of both end portions 12a, and as a result, the door guard bar 11
Will be twisted. Such a twist occurs after the second drawing process is completed, but by adding the sub-bead 16 as described above to this, a tensile stress acts toward the position where the bead 16 is formed. Compressive stress is reduced. When this is shown as experimental data, it decreases as shown by the C line (principal stress direction) and D line (main stress direction and 90 ° direction) in FIG.

Therefore, the twisting of the door guard bar 11 is prevented, and it is prevented that the door guard bar 11 is attached to the door panel, and a good product is obtained.

Finally, in the trimming process, the door guard bar 11 is trimmed all around to complete the manufacturing.

By the way, as in the above-described embodiment, the sub-bead 16 can be favorably reduced in residual compressive stress by performing the sub-bead 16 in the rest-like process after the formation of all the main beads 13, 14, 15, but is not limited to this. Alternatively, the sub-bead 16 may be formed simultaneously with the formation of the main beads 14 and 15 in the second drawing process. The experimental data of the residual compressive stress in this case are shown in Fig. 11 by E line (principal stress direction), F line (main stress direction and 90 ° direction)
Indicates the value as shown in. It can be clearly seen that the residual stress is reduced.

Although only three main beads are formed in the above embodiment, the number of main beads is not limited to this, and four or five main beads may be formed. In this case, the first main beads are formed every other one in the first drawing step, and then the adjacent second main beads are formed in the next drawing step. Of course, the first main beads formed in the first drawing step have a larger cross-sectional area and R shape than those in the product state. On the other hand, in order to further improve the strength of the door guard bar, it is possible to fix a reinforcement or a patch.

EFFECTS OF THE INVENTION As described above, according to the present invention, the first main bead is formed to have a larger cross-sectional area and R shape than the product state in the first drawing step, and the first main bead is formed in the next drawing step. When forming the adjacent second main beads,
By reducing the size of the first main bead, which has been formed large as described above, to a product state and supplying the reduced amount of material by flowing it to the side of the second main bead, the occurrence of cracks during the molding of the second main bead is prevented. It has the practically useful effect of being able to.

[Brief description of drawings]

1 to 11 are views showing an embodiment of an automobile door guard bar according to the present invention. FIG. 1 is a sectional view taken along the line II of FIG. 2, and FIG. 2 is a perspective view of the door guard bar. 3 is a sectional view taken along the line III-III in FIG. 2, and FIGS.
The figures are perspective views showing the manufacturing process of the door guard bar,
8 and 9 are explanatory views of the first and second draw dies, respectively, and FIG. 10 is a plan view showing a part of the door guard bar,
FIG. 11 is a graph showing the magnitude of residual compressive stress in each part of FIG. 10, and FIGS. 12 to 15 are views showing a conventional example.
Figure shows the front view of the automobile door, and Figure 13 shows XIII-XI in Figure 12.
A sectional view taken along line II, FIG. 14 is an exploded perspective view of the door guard bar, and FIG. 15 is a perspective view of the door guard bar. 11 ... Door guard bar 12 ... Guard bar main body 13 ... Main bead (first main bead) 14,15 ... Main bead (second main bead)

Claims (1)

[Claims] 1. A door for an automobile having a main body of a substantially rectangular shape made of a single sheet of high-strength steel and having a plurality of main beads arranged side by side in the longitudinal direction and mounted in the front-rear direction of the vehicle. A method of manufacturing a door guard bar for reinforcing the first main bead of the plurality of main beads, wherein the first main bead has a larger cross-sectional area and R than the product size state.
When forming the second main bead adjacent to the first main bead in the shape by the subsequent drawing process, the first main bead is corrected and reduced to a product state, and the first main bead is reduced. A method of manufacturing a door guard bar for an automobile, characterized in that the surplus material is formed by being supplied to the second main bead side.