JP2003147900A - Lightweight shape steel having high rigidity and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight shape steel while maintaining a sectional performance and an outer diameter dimension by varying in the thickness of a web and a flange. SOLUTION: The lightweight shape steel has a U-shaped and an L-shaped or a Z-shaped section formed by making bending work of a band steel in the direction of the width, both ends in the direction of the width of the band steel or the shape steel are pushed toward the center in the direction of the width, an area corresponding to part or the whole area of the flange of the shape steel is increasingly thickened than the thickness of the band steel material by thickening work, and part or the whole area of the flange is thicker than the web.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightweight shaped steel having a light weight while maintaining its cross-sectional performance and outer diameter, and a method for producing the same.

[0002]

2. Description of the Related Art Light-weight shaped steel formed by shaping a steel sheet into a predetermined cross-sectional shape has higher rigidity than a flat steel sheet,
Those having a cross-sectional shape such as a hat type, a U type, a Z type, and an L type are known. Since it is lightweight and has high strength, it is used as a structural material for buildings including houses. Since the conventional lightweight steel is manufactured by simply bending the steel strip in the width direction, each portion has a uniform thickness in the width direction. For example, the lightweight section steel having a U-shaped cross section has the same plate thickness for both the web and the flange. Therefore, it cannot be said that the sectional shape is efficient because of the sectional performance such as the second moment of area or the sectional modulus, and the sectional performance per weight is low.

[0003]

SUMMARY OF THE INVENTION The present invention has been devised to solve such a problem. By changing the wall thicknesses of the web and the flange, the cross-sectional performance and the outer diameter can be maintained. However, it is an object of the present invention to provide a lightweight shaped steel that can reduce the weight. In order to achieve the object, the highly rigid lightweight steel of the present invention has a U-shaped, L-shaped or Z-shaped cross section formed by bending a steel strip in the width direction, and a part or all of the flange. Is thicker than the web. It is preferable to use a plated steel strip as the steel strip.

For such a light-weight shaped steel, a roll or a die having a finite contact length in the longitudinal direction is used, and both widthwise ends of the steel strip or shaped steel are pressed toward the center in the widthwise direction. It is manufactured by thickening the region corresponding to a part or the whole area of the flange of the shaped steel to be thicker than the thickness of the material steel strip. A process of forming a steel strip into a lightweight shaped steel by roll forming, and a step of pressing a part or almost the entire area of the flange of the shaped steel in the width direction of the steel strip to increase the thickness to be thicker than the thickness of the raw steel strip. May be continuously performed.

[0005]

The operation will be described by taking as an example a lightweight channel steel having a typical U-shaped cross section of the lightweight steel. The lightweight channel steel is evaluated for its performance as a structural member by the second moment of area about a neutral axis parallel to the flange and passing through the center of the web.
The geometrical moments of inertia of the channel steels of the sizes shown in (a) and (b) of FIG. 1 are expressed by the following equations (1) and (2), respectively.

[0006] The respective cross-sectional areas are given by the following equations (3) and (4).

In the present invention, since the second moment of area is made equal in two channel steels, Ia = I
b. From the expressions (1) and (2), the relationship of the following expression (5) appears.

When the equation (4) is transformed using the equation (5), Therefore, as compared with the equation (1), if h ₂ / h ₃ is made larger than 1, the second moment of area is the same and the cross-sectional area is small, that is, the steel material can be lightened. h ₂ / h ₃
In order to make h larger than 1, h ₃ should be small, that is, the plate thickness of the flange should be thick. In the actual shaped steel, the corners are not right-angled and R is attached, so the above is not the case. It roughly shows the concept.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the inventor of the present invention investigated how to manufacture a highly rigid shaped steel using the same steel strip or steel plate. For example, as shown in FIG. 2A, the plate thickness is 4.5 mm, the web height is 200 mm, and the flange width is 75 m.
If a channel steel with a plate moment of 4 mm and a web height of 200 mm is produced so as to have the same second moment of inertia as the channel steel of m size, the flange width will be about 88 mm (Fig. 2 (b)). ). Therefore, the flange portion is shown in FIG.
In order to obtain a channel steel with a flange width of 75 mm, the flange tip end portion was pressed in the flange width direction so as to have a thickness of up to 1.5 times the plate thickness, and the thickness was gradually increased. However, the flange portion is not gradually distributed over the entire area, and in this case, an equivalent second moment of area could be obtained by increasing the thickness of the area of about 70% of the flange width from the flange tip (see FIG. 3). ).

As described above, in FIG. 2 (a) and FIG.
Although it is a channel steel with the same outer size with a web height of 200 mm and a flange width of 75 mm, the sectional area of the steel itself (that is, the weight of the steel material) is approximately 4.5 by increasing the thickness of the flange portion in a gradually increasing distribution. % Less channel steel with equivalent moment of inertia of area is obtained. In the actual shaped steel product, as described above, the corners are not right-angled but R (see FIG. 3), and since the thickened portion is formed inside the flange, the second moment of area is as described above. It is slightly smaller than the calculated value, and the cross-sectional reduction rate is about 3.7%.

Similarly, the plate thickness is 4 mm and the web height is 150 mm.
In the case of channel steel, the flange width of about 86 mm is pressed to 75 mm and the flange width after thickening from the flange tip is about 6
By increasing the thickness by 0%, the same external dimensions (web height 150 mm, flange width 75
It was possible to obtain a channel steel having an equivalent moment of inertia of area with a material that is approximately 3.6% less than that of the channel steel manufactured in (mm).

The case of increasing the thickness of a part of the flange with a uniform thickness was also examined. As shown in Fig. 4, a part of the flange with a plate thickness of 4 mm and a flange width before thickening of about 87 mm was increased by a maximum of 1.25 times at the tip of the flange, and the thickened width was increased to be uniform. When you eat meat, the web height is 200
In the case of channel steel of mm, by increasing the thickness of the area of about 65% of the flange width from the tip of the flange, the web height 20
With the same outer dimensions of 0 mm and a flange width of 75 mm, a grooved steel having an equivalent second moment of area can be obtained with a material that is 4.2% less than the lightweight grooved steel having a plate thickness of 4.5 mm.

Similarly, the plate thickness is 4 mm and the web height is 150 mm.
In the case of channel steel, the flange width of about 86 mm is pressed to 75 mm and the flange width after thickening from the flange tip is about 6
By increasing the thickness by 0%, the height of the web is 150 mm,
Flange width of 75 mm has the same external dimensions and plate thickness of 4.5 mm
A grooved steel having an equivalent moment of inertia of area can be obtained with a material that is about 3.6% less than the lightweight grooved steel of. The second moment of area of the lightweight channel steel having a thick flange having dimensions as shown in FIGS. 3 and 4 was calculated, and the differences from the conventional standard type are summarized in Table 1. In Table 1, the section modulus is also calculated and described.

[0014]

Next, a method of manufacturing a shaped steel in which the wall thickness of the flange portion is increased to increase the rigidity will be described.
As a method of increasing the thickness of a part of the flange, for example, the raw material before roll forming, during roll forming, or the width direction both ends corresponding to the flange tip of the shaped steel after roll forming, in the direction corresponding to the flange width direction. There is a method of pressing with a roll or a die having a finite length in the longitudinal direction of the material.
In the case of roll forming, the thickness can be increased continuously,
When a die is used, it is not realistic to press it in one step because it requires a long die and a large pressing force to form a shaped steel having a length of several meters. By using a mold having a finite length and dividing the shaped steel in the longitudinal direction and repeatedly pressing it, molding can be performed with a relatively low pressing force.

Since the contact length between the die and the material determines the region where the plastic deformation from the widthwise end of the flange extends, the wall thickness distribution of the flange can be controlled to some extent by the contact length of the die. When increasing the thickness by roll forming, the contact length L between the roll and the material is inevitably finite, and the length can be adjusted by the roll diameter and the reduction amount (see FIG. 5). In general, when the contact length L is shortened, the wall thickness of the flange has a distribution that gradually decreases from the tip of the flange as shown in FIG. 3, and conversely, when the contact length L is made longer, it is relatively uniform as shown in FIG. Tends to approach the distribution.

The thickness distribution of the flange after the actual thickness increase is shown in FIG.
Or something similar to Figure 4, or somewhere in between,
Alternatively, the distribution may be more complicated due to the buckling that accompanies the flange reduction. In any case, the sectional performance of the channel steel depends on the sectional area of the flange and is hardly affected by the plate thickness distribution itself. However, when used as a channel steel, it is generally preferable that the plate thickness of the flange is uniform from the viewpoints of spot welding to the flange, partial attachment, and the like.

When the thickened portion is formed on the flange, as shown in FIG. 5, the flange is expanded outward during the forming process of the shaped steel, and then the outer surface of the flange and the inner and outer surfaces of the web are rolled. When the flange is pressed down in a state of being restrained by a metal mold such as, the buckling is suppressed and a shaped steel having a good shape can be obtained. Although the above description has been made by taking the lightweight channel steel having a U-shaped cross section as an example, the present invention can be similarly applied to a lightweight steel having an L-shaped or Z-shaped cross section.

[0019]

As described above, considering the stress applied to the web and the flange, the thickness of the flange portion of each portion is made thicker than the thickness of the web portion so that the weight and the outer dimensions are the same. However, the second moment of area can be increased, whereby a lightweight steel with high sectional performance can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram for explaining changes in second moment of area due to differences in plate thickness.

FIG. 2 is a diagram for explaining the process of increasing the second moment of area by increasing the plate thickness of the flange.

[Fig. 3] Lightweight channel steel with a gradually increasing thickness on the flange

[Fig. 4] Lightweight channel steel with uniform thickness increase on the flange

FIG. 5 is a diagram illustrating a method of forming a thickened portion on a flange.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Asada             1 Tsurumachi, Amagasaki City, Hyogo Nisshin Steel Co., Ltd.             Company Technology Research Center F-term (reference) 2E163 FB04                 4E028 AA03

Claims (5)

[Claims] 1. A steel strip having a U-shaped, L-shaped or Z-shaped cross section formed by bending the steel strip in the width direction, wherein a part or all of the flange is thicker than the web. High-rigidity lightweight structural steel. 2. The high-rigidity lightweight shaped steel according to claim 1, wherein the steel strip is a plated steel strip. 3. A roll or a mold having a finite contact length in the longitudinal direction is used, and both ends in the width direction of the steel strip or the shape steel are pressed toward the center in the width direction. A method of manufacturing a light-weight shaped steel having high rigidity, which comprises thickening a region corresponding to a part or the whole region to a thickness thicker than that of a raw steel strip. 4. A step of forming a steel strip into a lightweight shaped steel by roll forming, and pressing a portion corresponding to a part or almost the entire area of the flange of the shaped steel in the width direction of the steel strip to make it more than the thickness of the raw steel strip. A method for manufacturing a light-section steel with high rigidity, characterized by continuously performing a step of thickening. 5. The method for producing a lightweight steel with high rigidity according to claim 3, wherein the material steel strip is a plated steel strip.