JPH0469014B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a structure of a press-formed product made of a steel plate, particularly a thin steel plate.

[Conventional technology]

Thin steel sheet press-formed products used for automobile bodies and the like need to be made as thin as possible from the viewpoint of weight reduction. However, ordinary steel plates are inferior in terms of strength, so high-strength steel plates have traditionally been used.

[Problem that the invention seeks to solve]

However, high-strength steel plates have poor press formability.
There were problems such as cracks occurring during press molding and poor shape fixability due to spring back. An object of the present invention is to provide a plastic molded product made of ordinary steel plate that can be made thin and secure the necessary strength without using a high-tensile steel plate.

[Means and actions for solving problems]

This invention was made by focusing on the above-mentioned conventional problems, and forms high-hardness molten beads in areas where strength is required in press-formed products made of ordinary steel sheets, thereby ensuring the necessary strength. However, it is an attempt to solve the above-mentioned problems.

The steel plate press-formed product according to the present invention forms linear high-hardness molten beads at predetermined locations where various strengths such as tensile rigidity, tensile strength, and buckling strength are required in the press-formed product made of ordinary steel plate. It is characterized by the fact that

To form a highly hard molten bead on a press-molded product, it is done by irradiating it with a laser beam, electron beam, plasma beam, etc. When using a plasma beam, the irradiated part is cooled by air cooling, water cooling, etc. Forced rapid cooling is desirable.
Note that the molten bead can be further hardened by applying a hardening member such as carbon or manganese to the surface of the press-formed product and then melting it.

It is easiest to process molten beads when they are formed in a linear shape, and a plurality of linear molten beads are formed in parallel at predetermined intervals at a predetermined location, and the area where these linear molten beads are formed is Tensile rigidity, tensile strength, buckling strength, etc. (hereinafter simply referred to as strength) have been improved, which in turn has increased the strength of press-formed products.

In addition, the strength of the area where a molten bead is formed (hereinafter referred to as a bead formation area) and the area where a molten bead is not formed (hereinafter referred to as a non-bead formation area) is different, and the bead formation area can be arbitrarily selected. By forming it in a certain position, the strength distribution of the press-formed product can be arbitrarily designed. For example, if the present invention is applied to an automobile body,
This means that the crash form at the time of a collision can be arbitrarily controlled.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

FIG. 1 shows the present invention applied to a front side member of an automobile.

In this figure, an outer surface area 1 of a front side member 10 formed by press-forming a thin mild steel plate.
A number of linear high-hardness molten beads 12 are formed in parallel at 0A and 10C. As described above, in this embodiment, the high-hardness molten bead 12 is formed almost entirely, and the overall buckling strength of the press-formed product 10 is increased, making it less likely to buckle.

Further, the outer surface region 10B does not have the molten bead 12 formed therein, and the buckling strength is correspondingly lower than that in the regions 10A and 10C in which the molten bead 12 is formed. Therefore, when a buckling load is applied, buckling occurs in the region 10B.

In this way, the buckling form of the front side member 10 during a collision can be controlled from aspects other than the shape of the press-formed product.

FIG. 2 shows another embodiment in which the present invention is applied to a front side member.

In this figure, an outer surface area 2 of a front side member 20 formed by press-forming a thin mild steel plate.
A plurality of high-hardness molten beads 22 are formed in parallel in each region 0B, 20D, 20F, and the remaining outer surface regions 20A, 20C, 20E,
No molten bead 22 is formed in 20G.

In this embodiment, areas 20B, 20D, 20F
The buckling strength of areas 20A, 20C, 20E, 20
G is higher than G, so when a buckling load is applied to the front side member 20, the area 20
A, 20C, 20E, and 20G are more likely to buckle, and areas that are more likely to buckle and areas that are less likely to buckle are formed alternately, and have the highest amount of impact force absorption against impact force (buckling load). It has become possible to control the buckling pattern so that

3 to 5 show an embodiment in which the present invention is applied to a side impact bar of an automobile.

In these figures, side impact bar 3
0 is attached to the outer panel of the front door 31, and is made of a thin steel plate that is press-formed into a corrugated cross-sectional shape so as to be able to withstand collision forces from the side, that is, to increase bending strength. Further, a plurality of high-hardness molten beads 32 are formed with a predetermined width along the longitudinal direction of the bar on the peak side 30A and the valley side 30B of the cross-sectional wave-shaped portion of the side impact bar 30. The bending strength against collision force (side impact force) is further increased.

In addition, in the above embodiment, the side impact bar 3
Although a linear molten bead 32 is formed over the entire waveform portion of the bar 30, since the position where the maximum bending stress occurs in response to a collision force from the side is the center of the bar 30, Forming a molten bead alone is also effective in increasing the bending strength.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, a high hardness molten bead is formed in the region where strength is required of a press-formed product made of ordinary steel plate, thereby ensuring the necessary strength. Therefore, it is possible to form a press-molded product that much thinner.

In addition, by appropriately selecting a high-hardness molten bead forming region, it is possible to obtain an effect that the strength is further excellent and that the deformation form of the press-formed product can be set arbitrarily.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention;
FIG. 2 is a perspective view showing a second embodiment of the invention, FIGS. 3 to 5 are views showing a third embodiment of the invention, FIG. 3 is a front view of the front door, and FIG. The figure is a perspective view of a side impact bar to which the present invention is applied.
FIG. 5 is a sectional view taken along the line - shown in FIG. 4. 10, 20...Front side member, 12,
22, 32... Molten bead, 30... Side impact bar, 30A... Mountain side of side impact bar, 30B... Valley side of side impact bar.

Claims (1)

[Claims] 1. A press-formed product made of ordinary steel plate, characterized by forming linear high-hardness molten beads at predetermined locations where various strengths such as tensile rigidity, tensile strength, and buckling strength are required. Steel plate press molded product.