JP7204562B2 - cold roll formed lip channel steel - Google Patents

Description

TECHNICAL FIELD The present invention relates to lip channel steel, and more particularly to cold roll formed lip channel steel having a thickness gradation cross section in which the plate thickness of the web is not uniform but is gradually reduced.

Roll-formed shaped steel (lightweight shaped steel) used as various structural members is required to have high cross-sectional performance with as small a cross-sectional area as possible, that is, to have high cross-sectional efficiency. At the same time, high productivity is required.
For example, JP-A-2003-100000 discloses a cold-formed shaped steel of unequal thickness for the purpose of obtaining a lightweight shaped steel with a high cross-sectional efficiency. This unequal-thickness cold-formed shaped steel is formed by bending a steel plate of unequal-thickness by cold forming to form a shaped steel having a cross-section having at least three sides, and parallel to the strong axis and the farthest It is an invention that the plate thickness of the sides is thicker than the other plate thicknesses.
Specifically, for example, as shown in FIG. 9 (FIGS. 2A, 2B, and 2C in Cited Document 1), for a general lip channel steel 2A, an irregular shape as shown in FIG. A uniform thickness steel plate 2C is cold-formed to form a unequal thickness cold formed lip channel steel 2B in which the flange 11 is a thick plate and the web 12 and the lip 13 are thin plates.
As a result, the bending resistance cross-sectional performance in the strong axis direction (web width direction) when used as a bending material is enhanced.

According to the drawing, the cross-sectional shape of the unequal-thickness cold-formed lip channel steel 2B in Patent Document 1 has a narrow range of plate thickness at the boundary between the thick plate portion and the thin plate portion, which is the bent portion. There is a step (rapid change in plate thickness in a narrow range).

Japanese Utility Model Laid-Open Showa 59-154518

As in the conventional art, if the boundary between the thick plate portion and the thin plate portion of the raw material unequal thickness steel plate 1C or the unequal thickness plate material 1 is stepped in a narrow range, when cold roll forming is performed various problems arise.
As in the conventional art, if the boundary between the thick plate portion and the thin plate portion of the raw material unequal thickness steel plate 1C or the unequal thickness plate material 1 is stepped in a narrow range, when cold roll forming is performed various problems arise.
(a) When cold roll forming a steel plate with a thickness difference, it is conceivable that the rolls (forming rolls) sharply come into contact with the steel plate in areas where the plate thickness changes rapidly in a narrow range, resulting in scratches on the steel plate. There is concern about the possibility of sticking and severe wear of the roll.
(b) At a portion where the plate thickness changes abruptly, contrary to the case where the roll sharply contacts the steel plate as described above, it is conceivable that the roll is formed with a clearance without contacting the steel plate. (or the shape becomes unstable).
(c) At the time of roll forming, stress is concentrated in a portion where the plate thickness changes rapidly in a narrow range, so there is a risk of deterioration of the material. In particular, in the uneven thickness cold-formed shaped steel described in Patent Document 1 and Patent Document 2, the plate thickness changes in the short bending portion between the flange of the thick plate portion and the web of the thin plate portion, so the stress Concentration is particularly noticeable on the thin plate side of the bend.
(d) When a load is applied after construction as a structural member, stress concentration is likely to occur in a portion where the plate thickness changes rapidly within a narrow range, affecting structural performance. In particular, in the uneven thickness cold-formed shaped steel described in Patent Document 1 and Patent Document 2, the plate thickness changes in the short bending portion between the flange of the thick plate portion and the web of the thin plate portion, so the stress Since the concentration is particularly on the thin plate side of the bending portion, its influence is large.
(e) If there is a stepped portion where the plate thickness changes rapidly in a narrow range, it is difficult to obtain a cold roll formed lip channel steel with a large difference between the maximum thickness and the minimum thickness.

The inventors of the present invention have recognized that the above-mentioned various problems occur during cold roll forming, and the thickness of the web is not a thin plate with a constant thickness, but a curvature toward the center of the web. The inventors have found that it is possible to further increase the cross-sectional efficiency by adopting a cross-sectional shape (plate thickness gradual change cross-section) that gradually changes in thickness while having a surface.
On the other hand, however, lip channels are generally loaded in a state in which two lip channels are tied upside down as shown in FIG. 6, which will be described later. Gradual-thickness cross-sectional portions 51a, 51a of the entire web excluding bent portions 54, 54' on both sides, such as 50, 50', which gradually change in thickness toward the center of the web while having a curved surface. ', a loading problem occurs.
That is, like the lip channel steels 50, 50' shown in FIG. Due to the gap δ between the lower lip channel steel 50 and the inner surface of the web 51 (plate thickness gradual cross-section portion 51a), the upper lip channel steel 50′ is loaded in an inclined state. It will be.

The present invention has been made based on the above background. To provide a cold roll-formed lip channel steel that improves cross-sectional efficiency compared to the conventional lip channel steel with a cross-sectional shape of equal thickness as a whole and does not cause loading problems. for the purpose.

The invention of claim 1 for solving the above-mentioned problem has a web having a plate thickness thinner than that of the flange, and the plate thickness of the web extends from the end point Q of each of the upper and lower flanges and the web to the bending portion. A lip channel steel having upper and lower plate thickness gradual cross-sections that gradually become thinner while having a curvature surface in a direction away from the end point Q of
The end point of each plate thickness gradual cross-sectional portion is located on the end point Q side of each of the bent portions from the position separated from the end point Q of the bent portion by the lip portion length C, and the plates above and below the web The plate thickness between the end points of the thickness gradual change section is uniform.

According to the cold roll-formed lip channel steel of the present invention, it is possible to achieve high cross-sectional efficiency while avoiding a decrease in productivity.
For example, in the case of channel steel for structural members that undergo bending, when the web width direction is used as the strong axis direction, the web is the thin plate side and the flange is the thick plate side, so the structural performance (strength The cross-sectional area can be reduced without reducing the rigidity in the axial direction (approximately the geometrical moment of inertia in the direction of the strong axis). That is, high cross-sectional efficiency can be achieved.

In addition, the web, which is the thin plate side, is not just a thin plate side (a thin side with a constant thickness as a whole), but is gradually thinned between the ends of the thin equal-thickness portion at the center of the web. Compared to the abrupt bending portion in 1, the plate thickness is gradually reduced over a wide range, and there is no stepped portion where the plate thickness changes abruptly over a narrow range.
That is, the bent portion in the cold roll-formed lip channel steel of the present invention is not a bent portion that abruptly changes from a thick plate cross section to a thin plate cross section, but a bent portion that is in a bent state close to a simple thick plate cross section. , the thickness of the thin plate edge gradually decreases from the bent portion near the thick plate cross-sectional bent portion to both ends of the equal-thickness portion in the central portion of the web.
Therefore, it is possible to eliminate the various fears that occur during cold roll forming when there is a stepped portion (therefore, the fear of lowering productivity) and the problems after construction, thereby avoiding the lowering of productivity.

By the way, as shown in FIG. 6, which will be described later, two lip channel steels are generally loaded in a state in which two lip channel steels are tied upside down. A loading problem arises with a cross-sectional shape that is progressively thinner and thinner.
That is, as shown in FIG. 8 to be described later, in two lip channel steels that are tied upside down, a gap is formed between the lip portion of the upper lip channel steel and the inner surface of the web of the lower lip channel steel. will cause the upper lip channel steel to be loaded at an angle.
However, as shown in FIG. 7, according to the lip channel steel of the present invention, the range of the plate thickness gradual cross-sectional portion 21a is the end point Q of the bent portion 14 on both sides of the web and the constant thickness portion 21b at the center of the web. The length L of the lip portion 13 is not greater than the length C of the lip portion 13, so that the lip portion 13' of the reversed upper lip channel portion 20' It does not rest on the plate thickness gradation section 21a, and no such loading problem occurs.

In addition, when a cold rolling stand is installed upstream of the roll forming stand and the lip channel steel of the present invention is manufactured from a general rolled steel plate having the same thickness as a whole, as in claim 2, Setting the position of the end point P of the thickness gradual change section 21a at a position 10 mm in the web width direction from the outer surface of the flange is effective for dual use of the cold rolling rolls used in the cold rolling stand.
That is, in the typical size of lip channel steel described in JIS G3350 (2017) lightweight steel for general structure, the shortest lip length is 10 mm, so the position of the end point P of the plate thickness gradual cross section 21a is If the position is 10 mm in the web width direction from the flange outer surface position, the material steel plate for the lip channel steel with a longer lip portion is cold rolled by using a roll for cold rolling the material steel plate in that case. (This is, of course, when solving the loading problem).

1 is a cross-sectional view of a lip channel steel according to one embodiment of the present invention; FIG. FIG. 4 is a cross-sectional view of a lip channel steel according to another embodiment of the present invention; (a) is an enlarged view of the bent portion of the lip channel steel of FIG. Fig. 10 is a diagram for explaining a case where the range of the bent portion is made slightly wider than 90° of (A); 1. It is a figure which shows the cross-sectional shape of the material steel plate (steel plate before a forming process) used as the raw material at the time of roll-forming the lip channel steel (indicated by the broken line) of FIG. FIG. 3 is a diagram showing a cross-sectional shape of a material steel plate (steel plate before forming process) that is a material for roll forming the lip channel steel (indicated by a broken line) in FIG. 2 . FIG. 10 is a diagram showing a loading mode that is generally performed when loading a lip channel steel having a normal cross-sectional shape and having an equal thickness throughout. FIG. 7 is a diagram illustrating how a pair of lip channels are tied together when the lip channels of FIG. 1 are loaded in a manner similar to that of FIG. 6; It is shown for comparison with the lip channel steel of the present invention. Figure 7 illustrates the tying of a pair of lip channels when loaded in a manner similar to Figure 6, but in this case the upper lip channel of the tying is tilted; . A conventional example (Patent Document 1) in which the web is thin and the flange is thick for the lip channel steel is described, and FIG. 2A, FIG. 2B and FIG. 2C in Patent Document 1 are reproduced.

Hereinafter, a mode for carrying out the cold roll-formed lip channel steel of the present invention will be described with reference to the drawings.

FIG. 1 shows a cold roll formed lip channel (hereinafter sometimes simply lip channel) 20 according to one embodiment of the present invention. This lip channel steel 20 has a cross-sectional shape with a flange 12 that is bent at right angles at bent portions 14 at both ends of a web 21 and a lip portion 13 that is bent inward at right angles at bent portions 15 at the ends of the flanges 12 .
The bent portions 14 and 15 in the embodiment of FIG. 1 have a standard bending radius R1 (2t= 2 x 3.5 mm = 7 mm) and a bend in the range of 90°.
The lip channel steel 20 of this embodiment has basic dimensions of web dimension H×flange dimension A×lip dimension C of 100 mm×50 mm×20 mm. The plate thickness t of the thick plate sides 12 and 13 is 3.5 mm. Both cross sections are vertically symmetrical.
The web 21 may refer to the range of the web dimension H or may refer to the portion excluding the bent portion. Further, when referring to the flange 12, there are cases where the range of the flange dimension A is indicated and cases where the portion excluding the bent portion is indicated.

In the lip channel steel 20 of FIG. 1, the web 21, which is the side of the thin plate, has an equal thickness portion 21b having a thickness t1 of 2 mm at the center portion. A section 21a with a gradually changing plate thickness is curved in an arc shape (the radius of curvature is indicated by R3) between Q and Q and becomes thinner.
FIG. 4 shows the cross-sectional shape of a material steel plate (steel plate before entering the forming stand) 20' before cold roll forming the lip channel steel 20. As shown in FIG. Portions corresponding to the respective portions of the lip channel steel 20 are indicated by the reference numerals of the respective portions.
In this embodiment, as a cold roll forming facility, a cold rolling stand installed upstream of the roll forming stand for forming the lip channel steel is used to form a general rolled steel plate having a uniform thickness as shown in FIG. A case of cold rolling into a cross-sectional shape is assumed. However, a material steel sheet having a cross-sectional shape such as that shown in FIG. 4 may be put into a roll forming stand without going through the cold rolling stand.

This lip channel steel 20 exerts its effect by using the width direction of the web 21 as a strong axis in building/civil engineering structures and other structures.
That is, since the web 21 is the thin plate side and the flange 12 is the thick plate side, the cross-sectional area can be reduced without deteriorating the structural performance (rigidity in the direction of the strong axis (approximately the moment of inertia of area in the direction of the strong axis)). can be done. That is, high cross-sectional efficiency can be achieved.
In addition, the web 21 is not just a thin plate side (a thin side with a constant thickness as a whole), but rather extends from the end point Q of the bent portion 14 toward the center of the web 21 (toward the direction away from the end point Q of the bent portion). In addition, since it is a plate thickness gradual change section that gradually becomes thinner while having a curved surface (that is, a plate thickness gradual change section that is thicker on the flange 12 side and gradually thinner while having a curved surface on the center side of the web 11), the geometrical moment of inertia This cross section is effective in reducing the cross-sectional area as much as possible without reducing the .

Further, the web 21, which is a thin plate side, does not become thin immediately from the bent portion 14, and does not have a stepped portion where the plate thickness changes abruptly within a narrow range. That is, this bent portion 14 is not a bent portion that abruptly changes from a thick plate cross section to a thin plate cross section, but is a bent portion that is in a bent state close to a simple bent portion of a thick plate cross section. After passing through the bent portion 14 near the bent portion of the plate cross section, the plate thickness gradually decreases.
Therefore, various fears that occur in cold roll forming when there is a stepped portion (thus, the fear of lowering productivity) and problems after construction are solved as follows (a) to (d). , a decrease in productivity can be avoided.
(b) The thickness gradually changes from the end point Q of the bent portion 14 to the uniform thickness portion at the center of the web, and the thickness gradually changes while having a curved surface. Since the rolls (forming rolls) do not sharply contact the steel plate, there is no risk of the raw steel plate being scratched or the rolls being severely worn.
(b) There is no risk that the roll will be formed with a clearance without coming into contact with the material steel plate, and therefore a desired cross-sectional shape can be stably obtained.
(c) The bent portion 14 itself is in a bent state similar to the bent portion of the cross section of a thick plate, and the plate thickness changes gradually from the end point Q of the bent portion to the uniform thickness portion at the center of the web while having a curved surface. Since the thickness does not change abruptly in a narrow range, the effect of stress concentration on the bending part and the thickness gradual cross section during roll forming is , the overall thickness is the same as in the case of lightweight shaped steel, and there is no particular problem of material deterioration.
(d) The degree of plastic working that occurs in the bent portion 14 and the plate thickness gradual cross-section portion during roll forming is the same as in the case of lightweight shaped steel with uniform thickness as a whole, and a load is applied after construction as a structural member. In this case, the effect of stress concentration on the bent portion and the plate thickness gradual cross-sectional portion is the same as in the case of a light-weight shaped steel with uniform thickness, so there is no problem of affecting the structural performance.
(e) The web 21, which is a thin plate edge, gradually decreases in thickness from the end point Q of the bent portion 14 in a bent state close to the bent portion of the thick plate cross section while having a curved surface. Since the plate thickness gradually decreases while having a curved surface, due to the effects of (a) to (d) above,
It is possible to set the plate thickness difference between the thick plate side and the thin plate side to be larger than when there is a stepped portion where the plate thickness changes abruptly in a narrow range. That is, it is possible to easily obtain a cold roll-formed lip channel steel with a large difference between the thickest and thinnest sections.

By the way, as shown in FIG. 6, two lip channel steels are generally loaded in a state in which two lip channel steels are tied upside down. As shown in (50'), the plate thickness gradually changes toward the center of the web between the bent portions 54 (54') on both sides of the web 51 (51') while having a curved surface. If the cross-sectional shape has a cross-sectional portion 51a (51a'), a loading problem occurs (in FIG. 8, the upper and lower lip channel steels that are tied together have the same shape, but for distinction, the upper Reversed lip channels are indicated with a "'" such as "50'").
That is, as shown in FIGS. 8(a) and 8(b), in two lip channel steels 50 and 50' tied upside down, the lip portion 53' of the upper lip channel steel 50' and the lower side Since a gap δ is generated between the lip channel steel 50 and the inner surface of the web 51 (plate thickness gradual cross section 51a), the upper lip channel steel 50′ is loaded in an inclined state. .
However, with the lip channel steel 20 of the present invention, the problem of tipping when loaded does not occur. That is, as shown in FIGS. 7(a) and 7(b), the range of the plate thickness gradual cross-sectional portion 21a is between the end points Q of the bent portions 14 on both sides of the web and both ends of the uniform thickness portion 21b at the central portion of the web. and its length L is not greater than (equal to or less than) the length C of the lip portion 13, so that the lip portion 13' of the inverted upper lip channel 20' is not placed on the plate thickness gradual change section 21a on the inner surface of the web. Therefore, the upper lip channel steel 20' is not tilted.
In FIG. 7, the position P' of the end of the flat portion of the lip portion 13' of the upper lip channel steel 21' (the end of the flat portion of the lip portion 13' excluding the bent portion 15') is It is shown as a case where the lip channel steel 20 is positioned exactly at the end P of the plate thickness gradual cross-sectional portion 21a (Also in FIG. 7, the upper and lower lip channel steels that are tied together have the same shape, For distinction, the upper reverse lip channels are shown with a "'" such as "20'").

Another embodiment of a lip channel steel 40 is shown in FIG. This lip channel steel 40 has the same web 11 and flange 12 as the lip channel steel 20 of FIG. .
The lip channel steel 40 of this embodiment has a lip portion 33 which is a thin plate side extending inwardly in parallel with the web 21 via the second bent portion 35 at the tip of the flange 12 .
The lip portion 33 as a whole is curved in an arc shape (the radius of curvature is indicated by R4) from the end point Q of the second bent portion 35 toward the tip of the lip portion, and the thickness of the lip portion 33 is reduced. In other words, the entire lip portion 33 (the entire portion excluding the bent portion 35) is a thickness gradual change section portion 33a. The plate thickness at the bent portion 35 of the lip portion 33 is the same plate thickness as the flange 12 (t=3.5 mm), but the plate thickness t4 at the tip of the lip portion 33 is 2 mm.
FIG. 5 shows the cross-sectional shape of a material steel plate 40' before the cold roll forming of the lip channel steel 40. As shown in FIG. Portions corresponding to the respective portions of the lip channel steel 40 are indicated by the reference numerals of the respective portions.

The position of the terminal point Q of the bent portion 14 at both ends of the web shown in each of the examples of FIGS. is not necessarily geometrically accurate, it may be positioned at an angle (θ'') slightly smaller than 90°, such as the position indicated by Q'' in FIG. , may be positioned at an angle (.theta.''') slightly larger than 90.degree., such as the position indicated by Q''' in FIG. The illustrated example shows the range of the bent portion 14 as the position where the arc of the outer radius (the bending radius R1 of the outer surface) of the bent portion 14 intersects the inner surface of the bent portion.

20, 40 Lip channel steel
20', 40' Material steel plate (steel plate before forming)
21 Web 21a Thickness gradual change section 21b Equal thickness portion 12 Flanges 13, 33 Lip portions 14, 15, 35 Bending portions Q, Q'', Q''' (on both ends of the web) Bending end point Q' (lip portion End points R1, R3, R4 of bent portions (at the base end) Curvature radii t, t1, t4 Plate thickness L Length of plate thickness gradual cross-section (distance in web width direction)
P end point P' of plate thickness gradual cross-section part position of the end of the flat part of the lip part 13' of the upper lip channel steel 21' (Fig. 7)

Claims (2)

It has a web with a plate thickness thinner than the plate thickness of the flange, and the plate thickness of the web is in the direction away from the end point Q of the bent portion of the upper and lower flanges and the web, respectively, and the curvature A lip channel steel having upper and lower plate thickness graded cross sections that gradually become thinner while having a face,
The end point of each plate thickness gradual cross-sectional portion is located on the end point Q side of each of the bent portions from the position separated from the end point Q of the bent portion by the lip portion length C, and the plates above and below the web A cold roll-formed lip channel steel characterized in that the plate thickness between the end points of the thickness gradation section is uniform. 2. The cold roll formed lip channel steel according to claim 1, wherein the minimum value of the distance from the flange outer surface position to the end point of the plate thickness gradual section is 10 mm.

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