JPS63215419A - Automobile door guard bar and its manufacture - Google Patents

Abstract

PURPOSE:To prevent the generation of torsion, by forming a rectangular guard bar main unit from one sheet of high tension steel plate and parallelly providing plural main beads in the lengthwise direction while forming subbeads crossing at a right angle with the main beads in the vicinity of an end part in the peripheral edge of the guard bar main unit. CONSTITUTION:A high tension steel plate is formed into a rectangular shape, obtaining a door guard bar 11. And main beads 13-15 are parallelly provided in the lengthwise direction between both end parts 12a of a main unit 12. Further subbeads 16... are formed in a direction crossing at a right angle with the main beads 13-15 in a peripheral edge part 12b of the guard bar main unit 12 further in its both end parts 12a and central part. By this constitution, the door guard bar can be prevented from torsion by enabling residual compression stress, generated in the guard bar main unit, to be reduced. While the door guard bar can be manufactured easily and in light weight by integral molding.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a door guard bar that mainly aims to improve the strength of an automobile door against a side collision of a vehicle, and a method for manufacturing the door guard bar.

Prior Art Conventional devices of this kind include, for example, those shown in FIGS. 12 to 15. An automobile door l is mainly formed by an outer panel 2 and an inner panel 3,
In the space A formed by both panels 2 and 3, there is a 12th
As shown in the drawings and FIG. 13, a door guard bar 4 is arranged along the longitudinal direction of the vehicle.

This door guard bar 4 is provided mainly to reinforce the door 1 from being crushed in the event of a side collision of a vehicle, and as shown in FIG. 14, it is composed of a guard bar body 5 and a reinforcement 6. There is. This guard bar body 5
is assembled by spot welding the intermediate portion 5a divided into three parts and the front and rear ends 5b, 5c, and further, by spot welding the reinforcement 6 to the guard bar main body 5, as shown in FIG. The door guard bar 4 is assembled as shown in the figure. And this door guard bar 4
The front and rear ends 5b and 5c of the door 1 are fixed to the inner panel 3 of the door 1.

In addition, as for this kind of thing, for example,
There is one described in 8414 publication.

Problems to be Solved by the Invention However, since such a door guard bar 4 is composed of four parts in total, in order to manufacture this door guard bar 4, each of the four parts must be press-molded. In addition, in order to weld separated parts, it is necessary to position these parts, which requires a positioning device. Manufacturing the door guard bar 4 is difficult. Furthermore, since it is a regular steel plate, it must be thicker to ensure strength, which increases weight.
There is a problem.

In order to solve this problem, the first invention provides a method for disposing a door along the longitudinal direction of the vehicle in a space formed by an outer panel and an inner panel of an automobile door. In the door guard bar installed to reinforce the door, a generally rectangular guard bar body is formed of a single high-tensile steel plate, and a plurality of main beads extending in the longitudinal direction are formed between both ends of the guard bar body. The automobile door guard bar is characterized in that sub-beads arranged in parallel and substantially perpendicular to the main bead are formed at the peripheral edge of the guard bar main body and at least near the end.

Further, in the second invention, a roughly rectangular guard bar body is formed from a single high-tensile steel plate, and then a plurality of main beads are drawn in parallel along the longitudinal direction of the guard bar body, and then Further, the present invention is characterized in that a sub-bead substantially perpendicular to the main bead is formed at the peripheral edge of the guard bar body and at least near the end.

According to the first invention, when a plurality of main beads are formed on the guard bar body, which is a high-tensile steel plate, to improve rigidity, a large residual compressive stress is generated especially at the end of the guard bar body. Twisting occurs in the main body. However, by forming sub-beads that are substantially perpendicular to the main bead at the peripheral edge of the guard bar body and at least near the ends, the material is pulled toward the sub-bead formation area, resulting in residual compressive stress at the ends. is reduced. Therefore, twisting of the door guard bar is prevented.

By integrally molding the door guard bar with a high-tensile steel plate in this manner, strength is ensured, and the number of parts and weight can be reduced.

According to the second invention, after forming a main bead on the guard bar main body made of a high-tensile steel plate, a sub-bead substantially orthogonal to the main bead is formed at the peripheral edge of the guard bar main body, and at least near the end. As a result, the residual compressive stress generated by the formation of the main bead is effectively reduced by the sub-beads formed thereafter, which is more effective in preventing twisting of the door guard bar.

Inu Eiko Below, Part 1. The second invention will be explained based on an example.

First, an embodiment of the door guard bar of the first invention will be described.

This door guard bar 11 is disposed along the longitudinal direction of the vehicle in a space formed by an outer panel and an inner panel of an automobile door, as in the conventional case.

As shown in FIGS. 1 to 3, this door guard bar 11 is made of a single high-tensile steel plate, and the high-tensile steel plate has a tensile strength of, for example, 80 kg.
/ n + m 2 or more are used. This door guard bar 11 has a guard bar main body j2 formed in a roughly rectangular shape, and three main beads 13, 1.4, 1.5 arranged in parallel along the longitudinal direction between both ends 1.2a of the main body 12. has been done. The guard bar main body 12 has a length of about 1000 mm and a width of about 180 mm. Further, both end portions 12a serve as attachment portions to a door panel (not shown). Furthermore, a total of ten sub-beads 16 are formed on the guard bar main body 12 in a direction substantially orthogonal to the main beads 13, 14, 15. Specifically, the sub-beads 16 are formed at the peripheral edge 12b of the guard bar main body 12, near both ends 12a, and at the center.

Two are formed near both ends 12a, and one is formed in the center.

Next, an embodiment of a method for manufacturing a door guard bar according to the second invention will be described.

First, as shown in FIG. 4, a central main bead 13 is formed on the rectangular guard bar main body 12 by drawing in a first drawing step.

The first draw mold 17 that performs this molding has a configuration as shown in FIG. That is, in the figure, reference numeral 18 is an upper mold plate, and 19 is a lower mold plate. A die 20 in which one bead forming recess 20a is formed is fixed to this upper mold plate 18, while a lower mold plate 1- One punch 21 is fixed to 19 to be inserted into the bead forming recess 20a. Further, a blank holder 22 (wrinkle suppressor) that holds the blank (guard bar body 12) between the die 20 and the die 20 is disposed via a cushion pin 23.

During press forming, the guard bar body 1, which is a high-tensile steel plate, is
2 on the blank holder 22 and lowering the die 20, the punch 21 is placed in the bead forming recess 20a.
to form the central main bead 13 (
(See Figure 4). At this time, as the die 20 is lowered, the blank holder 22 is pushed, so that the holder 22 is lowered via the cushion pin 23.

In this case, the cross-sectional shape of the central main bead 13 is as follows.

As shown by the two-dot chain line in the figure, the cross-sectional area and radius are larger than the cross-sectional shape in the product state shown by the solid line in FIG.

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

The second draw mold 24 that performs this molding has a configuration as shown in FIG. 9. That is, in the figure, reference numeral 25 is an upper mold plate, and 26 is a lower mold plate. A die 27 in which three bead forming recesses 27a are formed is fixed to the upper mold plate 25, and the lower mold plate 26 is fixed to the die 27. Three punches 28 are fixed to be inserted into the bead forming recess 27a. Furthermore, the blank holder 29 is attached to the cushion pin 3.
0.

During press forming, each punch 28 is inserted into each bead forming recess 27a, and the main beads 14 and 15 on both sides and the central main bead 13 are formed.

At this time, the main beads 14 and 15 on both sides are formed to have a cross-sectional shape substantially in the product state. On the other hand, the central main bead 13 is formed in the first draw step to have a larger cross-sectional area and R shape than the cross-section in the product state, and this is corrected by the second draw mold 24 to the cross-sectional shape approximately in the product state. Reduced. Then, the reduced material flows and is supplied to the main beads 14 and 15 on both sides. This flow is
This can be done well by increasing the radius of the radius.

If the material on the central main bead 13 side flows to the main beads 14 and 15 on both sides in this way, when forming the main beads 14 and 15 on both sides, this bead 1
4, 15, no cracks occur.

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

In other words, the main bead 1 is formed by press forming a high tensile strength steel plate.
3, 14, and 15, a compressive residual stress larger than that of a normal steel plate is generated. According to experimental data such as that shown in FIG. 11, this stress is generated at portion A in FIG.

When measuring at B, C, D, E, and F, the compressive stress in the principal stress direction is shown as a solid line in Figure 2, and the stress in the 90° direction to this principal stress direction is as shown in the open line in the figure. Show value. Looking at this, the stress is particularly large at the portion E of both ends 12a, and as a result, the door guard bar 11 is twisted. Such twisting occurs after the completion of the second draw step, but by adding the above-mentioned sub-bead 16 here, tensile stress acts toward the bead 16 formation position, so the above-mentioned twist occurs. Residual compressive stress is reduced.

If this is shown by experimental data, it will decrease as shown by the C line (principal stress direction) and the second line (direction 90 degrees from the principal stress direction) in FIG.

Therefore, the door guard bar 11 is prevented from twisting, and the installation to the door panel is prevented from being supported, so that a good product can be obtained.

Finally, the entire circumference of the door guard bar 11 is trimmed in an L-rimming step to complete the manufacturing process.

By the way, residual compressive stress can be better reduced by performing the sub-bead 16 in the restriking process after the formation of all the main beads 13, 14, and 15, as in the above embodiment, but the present invention is not limited to this. Instead, the sub-beads 16 can be formed simultaneously with the formation of the main beads 14 and 15 in the second draw step. The experimental data of the residual compressive stress in this case shows values as shown in the ho (principal stress direction) line and the f (90° direction from the principal stress direction) in FIG. 11. It can be seen that the residual stress has clearly decreased.

In the above embodiment, only three main beads are formed, but the present invention is not limited to this, and four or five main beads may be formed. In this case, main beads are formed every other time in the first draw step, and then adjacent main beads are formed in the next draw step. Of course, the main bead formed in the first drawing step has a larger cross-sectional area and radius than the main bead in the product state. On the other hand, in order to further improve the strength of the door guard bar, reinforcement or patches may be fixed.

As described in detail, according to the first invention of the door guard bar, sub-beads that are substantially orthogonal to the main bead are formed on the guard bar body made of high-strength steel plate at the periphery of the guard bar body and at least at the ends. By forming the door guard bar nearby, residual compressive stress generated in the guard bar body can be reduced, and twisting of the door guard bar can be prevented. Furthermore, since it is integrally molded, it is easy to manufacture, and since high-tensile steel plates are used, it is lightweight and strong. Further, according to the second invention of the method for manufacturing a door guard bar, the sub-beads are formed after the main bead is formed on the guard bar body.
This has a practically beneficial effect in that the residual compressive stress generated during main bead molding can be favorably reduced by the subsequently formed sub-beads.

[Brief explanation of the drawing]

Figures 1 to 11 are 1. FIG. 1 is a perspective view of the door guard bar for an automobile according to the second invention and a method for manufacturing the same. Figure 2 is a cross-sectional view along the ■-shore line in Figure 1, and Figure 3 is a cross-sectional view along the shoreline of Figure 1.
4 to 7 are perspective views showing the manufacturing process of the door guard bar, and FIGS. 8 and 9 are sectional views taken along the line m-m in the figure, respectively. Explanatory diagram,
Fig. 10 is a plan view showing a part of the door guard bar;
The figure is a graph showing the magnitude of the residual compressive stress at each part in Fig. 10, Fig. 12 to Fig. 15 are views showing conventional examples, and Fig. 12 is a front view of an automobile door. Figure 13 is a sectional view taken along the xm-xm line in Figure 12, Figure 14 is an exploded perspective view of the door guard bar, and Figure 14 is an exploded perspective view of the door guard bar.
FIG. 5 is a perspective view of the same door guard bar. , 11...Door guard bar 12...Guard bar body 12a...End portion 12b...Peripheral portion 13.14.15...Main bead 16...Sub bead UG3-215419 (6) wiJJ /A5
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Claims (2)

[Claims] (1) A door guard bar that is arranged in the space formed by the outer panel and the inner panel of an automobile door along the longitudinal direction of the vehicle to reinforce the door, is made of a single high-tensile steel plate and is approximately rectangular. A guard bar main body having a shape is formed, and a plurality of main beads along the longitudinal direction are arranged in parallel between both ends of the guard bar main body, and sub-beads substantially orthogonal to the main beads are arranged at the peripheral edge of the guard bar main body, A door guard bar for an automobile, characterized in that the door guard bar is formed at least near an end. (2) A roughly rectangular guard bar body is formed from a single high-tensile steel plate, and then a plurality of main beads along the longitudinal direction are drawn in parallel on the guard bar body, and then the main beads A method for manufacturing a door guard bar for an automobile, characterized in that a sub-bead substantially orthogonal to the guard bar body is formed at a peripheral edge of the guard bar main body and at least near an end.