KR100480228B1 - Method of correcting u-shaped steel sheet pile - Google Patents

Abstract

A technology for efficiently correcting bending and reverse bending of U-shaped steel piles, especially U-shaped steel piles with arm parts, has been developed.

For bending, press the outer surface of one flange of the steel pile plate, and press the other inner surface of the flange, while reverse bending, in addition to the web portion and the flange portion of the U-shaped steel pile plate, restrains the arm from the up and down direction. Use a roller.

Description

교정 Method of straightening steel file plate {METHOD OF CORRECTING U-SHAPED STEEL SHEET PILE}

Conventionally, a steel sheet pile manufactured by hot rolling and cut to a predetermined length generates shape defects such as reverse bending and bending in the longitudinal direction due to internal stress as cooling progresses. Here, "warping" refers to the bending of the edge which is largely bent in a direction perpendicular to the pile plate wall 2 of the U-shaped steel pile plate 1 as indicated by the symbol C in FIG. Iii), the term "bending" means that the edge is bent in a large parallel direction with respect to the pile plate wall 2 of the U-shaped steel sheet 1, as indicated by the symbol (B) of FIG. It means bending. Under the JIS A 5528 standard, the bending of U-shaped steel pile plate is 0.10% or less in total length X 0.12% for steel plate piles of 10 m or less in length, and (0.1m in total length)-0.10% + 12 mm for steel pile plates exceeding 10 m. It is prescribed | regulated below, and also about reverse bending, it is prescribed | regulated to the length X 0.25% or less for the steel plate of length 10m or less, and the thing exceeding 10m (length 10m) X 0.20% + 25mm or less.

The correction of such a shape defect is generally performed by a roller straightener. For this roller straightener, for example, four upper rollers and three lower rollers are arranged in a zigzag shape, so that the front and rear ends of the steel pile plate can exhibit sufficient correction effect. none.

In particular, the reverse bending and bending defects of the front and rear ends are difficult to be corrected by the roller straightener, and thus, the back and forth ends are generally corrected by the chiseling press straightener after the roller straightening.

3 shows a calibration operation by such a press straightener when bending occurs in the U-shaped steel pile plate 1, which is a material to be calibrated. In the case of the example of illustration, the press rod (not shown) which presses a press pressure in the direction of an arrow through the jig 5 is provided, and as shown in the opposite side, the U-shaped steel pile plate 1 which is a to-be-calibrated material 1 The jig 6, 8 supporting the one flange outer surface 4 of the flange is provided at two places to suppress the movement of the material to be calibrated.

However, even in the steel pile plate, in the case of a U-shaped steel pile plate having a large rigidity against bending in the left and right direction, as shown in Figs. 4A and 4B, the flange outer surface 4 on one side (see Fig. 3). ) Is not corrected by pressing with a press, and the cross section in the direction in which the width of the material to be calibrated becomes narrow so that the reference width W ₀ shown in FIG. 4 (a) becomes the width W ₁ indicated by the dotted line. In addition to deforming the shape, problems such as causing local concavity D in the pressed flange portion as shown in Fig. 4 (b) have arisen. This problem was particularly remarkable when trying to correct bending of a U-shaped steel pile plate having an arm portion between a flange portion and a joint portion.

On the other hand, several methods have already been proposed in the conventional method for correcting the reverse bending of a U-shaped steel plate, for example, Japanese Patent Laid-Open No. 61-63316 discloses a web portion and a flange portion of a U-shaped steel plate. In a pair of upper and lower straightening rollers having a clamping portion to be clamped, it is proposed to provide a joint constraining portion that restrains the joint portion of the U-shaped steel pile plate adjacent to both sides of the upper and lower straightening rollers. The same is also proposed in Japanese Laid-Open Patent Publication No. 55-70418.

For example, as shown in FIG. 5, the straightening roller 10 of the U-shaped steel pile plate is a straightening roller 10a that separates the outside of the web part 12, the flange part 14, and the joint part 16, respectively. , 10b) and the roller 18, which restrains the outside of the joint portion 16, to correct the bending by repeating bending up and down, left and right while restraining the roller 18, and adjusts the size of the entire width of the product. It is designed to be. Since the bending correction is performed while restraining the web portion and the flange portion as described above, the cross-sectional shape of the product is not deformed and is corrected.

However, in the case of the U-shaped steel pile plate having the arm portion 19 between the joint portion 16 and the flange portion 14, as shown in FIG. It turned out to be different from the desired product cross section.

The present invention relates to a method for calibrating a U-shaped steel pile plate having, for example, an arm portion between a flange portion and a joint portion among U-shaped steel sheet piles used for civil engineering and construction. .

The first object of the present invention is to provide a new calibration method and a jig used therein, which solve the shortcomings of the right and left 'bending' of the U-shaped steel plate in the conventional method, and the defect of the jig used for the calibration. will be.

A specific object of the present invention is a calibration capable of efficiently correcting bending of a steel pile plate having a large bending stiffness in the product direction, such as a U-shaped steel pile plate having a female portion between a flange portion and a joint portion. A method and a jig used therein are provided.

A second object of the present invention is to provide a roller straightening method which can correct the warping of a U-shaped steel pile plate having arm parts without deforming the cross-sectional shape.

MEANS TO SOLVE THE PROBLEM In order to easily press-correct the bending of the steel pile board with large bending rigidity of a product lateral direction, it is effective to press one flange outer surface at the same time and to press another flange inner surface simultaneously. Based on this, the present invention has been completed.

In addition, the present inventor has repeatedly studied the problem that the angle of the flange portion and the joint portion is different from the intended angle when roller correction of the reverse bending of the U-shaped steel sheet plate having a female portion, and only the web portion and the flange portion are simply It is not sufficient to limit the cross section only, so that the cross section is restricted including the arm part. Thus, the upper and lower parts of the roller, which constrains the web part, the flange part, and the arm part, can be precisely corrected. Find out and complete the present invention.

Here, the present invention is a method for correcting the bending in the left and right directions caused by the hot rolling process of the U-shaped steel pile plate, while pressing the outer surface of one flange of the steel pile plate, characterized in that for pressing the inner surface of the other flange It is a calibration method of U-shaped steel pile plate.

In another aspect, the present invention relates to a first jig having a surface for pressing the outer surface of one flange of the U-shaped steel pile plate, and a second jig having a surface connected to the first jig and pressing the inner surface of the other flange. It is a calibration jig of a U-shaped steel pile plate, characterized in that the combination of both.

According to a suitable aspect of the present invention, with respect to the first jig having a surface for pressing the flange outer surface of the U-shaped steel pile plate, a fitting portion capable of attaching and detaching a second jig for pressing the inner surface of the flange is connected to both jigs. You may install in a part.

In addition, according to another suitable aspect, the adjustment mechanism which can change the relative position of the width direction of the product of the 2nd jig which presses the inner surface of a flange with respect to the 1st jig which has the surface which presses the flange outer surface of a U-shaped steel pile board is supported. It may be installed at its connecting portion.

In another aspect, the present invention is a roller calibration method of a U-shaped steel pile plate consisting of a web portion, a flange portion, a joint portion and having a female portion between the joint portion and the flange portion, wherein the arm portion is added in the vertical direction in addition to the web portion and the flange portion. A roller straightening method of a U-shaped steel pile plate having a female portion, characterized in that a restraining straightening roller, preferably a straightening roller in which each of the upper and lower rollers is integrated.

According to a suitable aspect of the present invention, when restraining the arm portion between the flange portion and the joint portion, a straightening roller which restrains in the up and down direction by giving an angle different from the product cross section may be used.

As described above, according to the roller calibration method according to the present invention, a straightening roller for bending correction by repeating the bending of the upper and lower sides and the left and right sides of the U-shaped steel pile plate having arm portions restrains the rollers that restrain the upper side of the U-shaped steel pile plate and the lower side. It consists of the roller to make, and these are arranged in the zigzag shape up-and-down roller.

(The best form to carry out invention)

According to the calibration method of the present invention, the press force indicated by the arrow in FIG. 7 pushes the outer surface 22 of one flange 21 of the U-shaped steel pile 20 as the material to be calibrated, and at the same time, Since the inner surface 23 of the flange 21 is pushed in the same direction, the external force is not concentrated on only one of the flanges 21 and 21, so that the width of the product is narrowed or the flange 21, No local deformation, such as local recesses, is to occur in (21).

In this case, the press force for pushing the outer surface 22 of one flange 21 and the press force for pushing the inner surface 23 of the flange 21 may be the same or somewhat different. In order to prevent deformation, it is good to press both sides with the same press force as much as possible.

In view of this point in the conventional method, since the pressing force is applied only to the outer surface of one flange of the U-shaped steel pile plate 1 as shown in Fig. 3, the recessed part local to the flange on the side pressed as shown in Fig. 4 (b). Local deformation such as (凹) occurs.

8 shows an example of a jig used in the calibration method according to the present invention, wherein a first jig for contacting and pressing the flange 21 of the U-shaped steel pile plate 20 as a material to be calibrated is pressed. 24 and the second jig 25 for pressing and contacting the inner surface 23 of the other flange 21 across the flange 21. Hereinafter, the first jig will be simply called jig A and the second jig will be called jig B.

In Fig. 8, the jig A and the jig B are properly connected with the connecting portion 26, for example, the bolt 28 through the threaded hole 27 formed on the jig B side by fitting the jig A, B properly. It may be fixed with. As such a connection form, it is good also as an integral structure, In addition, simple fitting, coupling by a pin and a pin hole, etc. can also be considered. However, the above-described fitting screw type is preferable as a simple and reliable structure.

In this case, in the case of the illustrated example, press force is applied in the direction of the arrow to the press ramhead connecting portion 29 installed on the jig A, and the same press force is applied to the jig A and B in the same direction to press both flange faces, respectively. The calibration method of the invention is carried out.

The jig A and the jig B have a structure that can be attached and detached at the connecting portion in the illustrated example for ease of handling, but may be of course integral.

In addition, as another embodiment, jig A and jig B may be configured to allow relative positioning of jig A and jig B in the width direction of the product by allowing the fitting portions of the two jigs to be spaced apart instead of being joined by the connecting portion. do. As a result, in response to the dimensional change (width change) of the material to be corrected, the press force when pressing the outer surface of the flange and the inner surface of the other flange at the same time is appropriately distributed, so that local deformation of the rolled material does not occur. You can correct the bends.

In this embodiment, as shown in Fig. 9, the connecting portion 26 of the jig A 24 and the jig B 25 is a kind of slide type so that fine adjustment can be made in the direction of the arrow, for example, a screw type fixing mechanism ( (Not shown) may be provided.

In any case, in order to correct the bending of the U-shaped steel pile plate by the press calibration method according to the present invention, as shown in FIG. 8, when the U-shaped steel pile plate 20 runs on the conveying roller R and comes to a predetermined position, Fixing is first performed by a jig composed of a combination of jigs A and B, and then press force is applied in the direction of the arrow in the figure. At this time, the fixing position by a jig is used, for example, by attaching one to the press pressing side and two to the support side of the material to be calibrated, as shown in FIG. 3. However, in the specific calibration operation is the same as the conventional one, the above description is omitted.

8 illustrates a steel pile plate having a female portion between the joint portion and the flange as the U-shaped steel pile plate, which may be a general U-shaped steel pile plate (without the above-mentioned female portion), and the jig shape is slightly changed in accordance with the product shape. It can carry out, and the effect by this invention is the same. In addition, although the example of the U type was shown as the attitude | position of the to-be-calibrated material in the example of illustration, even if it is an inverted U-type attitude, it is only necessary to invert the jig up and down according to the shape of the to-be-calibrated material.

Next, a roller calibration method for correcting the warping of the U-shaped steel pile plate will be described.

Figure 10 is an explanatory view of the arrangement of the calibration roller of the U-shaped steel pile plate having an arm as an example of the calibration roller according to the present invention. In the drawing, the U-shaped steel pile plate having the web part 30, the flange part 32, the arm part 34 and the joint part 35 has the upper rollers 36 and 36 and the lower rollers 38 and 38, and The web part, the flange part, and the arm part are restrained by the outer roller 40. In the example of illustration, the upper and lower calibration rollers 36 and 38 are integrally comprised so that the web part 30 and the flange part 32 may be restrained by the same roller, respectively.

In addition, if the angle of the arm part 34 and the flange part 32 before the calibration is different from that of the final product, the taper is repeatedly applied to the part restraining the arm part 34 of the rollers 36 and 38, thereby repeatedly bending and You may calibrate so that it may become the same angle as a product.

11 (a) and 11 (b) show one example of a calibration roller according to the present invention in such a case. The angles to the rollers 36 and 38, respectively, as compared to the case of FIG. Gave a taper of different.

In any case, in addition to the web part and the flange part, a straightening roller which restrains the arm part from the up and down direction is used. In particular, in the case of Figs. 11 (a) and 11 (b), when the arm part between the flange part and the joint part is restrained, A straightening roller that constrains up and down with an angle different from the cross section is used.

In addition, in the above-described example, the upper and lower rollers 36 and 38 are drawn as if the respective roller shafts are arranged to coincide with the vertical direction, but in practice, the upper and lower rollers are arranged in a zigzag shape.

Hereinbelow, the principle in which roller calibration is effectively performed by such restraint will be described.

In other words, the repeated bending correction is performed by three-point support by the top and bottom rollers arranged in a zigzag manner. Considering the case where the point is at the lower roller and the inversion is at the upper roller, as shown in FIG. When the arm part 34 is not restrained, the angle formed by the arm part 34 and the flange part 32 becomes small, that is, it is deformed in the direction in which the rising angle θ of the arm part 34 becomes large. That is, the arm 34 is deformed in the direction of the arrow in the figure. However, when the upper portion 34 is restrained from above by the present invention, the cross-sectional shape of the U-shaped steel pile plate is maintained without being deformed.

In addition, when the point is at the upper roller and the station is at the lower roller, as shown in FIG. 13, when the arm 34 is not restrained, the angle between the arm 34 and the flange 36 is increased, that is, the arm ( 34) is deformed in the direction in which the downward angle θ becomes large. That is, the arm 34 is deformed in the direction of the arrow in the figure. However, the cross-sectional shape in the case of restraining the arm 34 according to the present invention is maintained without deforming.

Therefore, as in the present invention, the arm portion together with the web portion and the flange portion, preferably the upper portion and the web portion and the flange portion by the same roller, without damaging the cross-sectional shape of the feature as in the case of Figs. You can correct it. In particular, by restraining the entire cross section except the joint part in a roller ball shape, not only the up and down reverse bending of the U-shaped steel pile plate but also the light left and right bends can be effectively corrected.

As described above, according to the present invention, even when the U-shaped steel plate having a higher rigidity against bending and inverse bending than the U-shaped steel plate without the arm part is easily removed from the light bend and the right and left bending by press or roller calibration. The angle of the arm can then be kept constant.

The working examples of the present invention will be described in detail by the following examples.

Example 1

The result of applying the press calibration method of this invention to the U-shaped steel pile plate which has a female part between a joint part and a flange part is illustrated below.

The size of the material to be calibrated is shown in Table 1, and the press calibration was performed using a press machine having a horizontal hydraulic cylinder, and the jig spacing (corresponding to the distance of jigs 6 and 8 in FIG. 3) of the supporting side was 1.2 m.

As a calibration method, in order to remove the bend over the entire length of the material to be calibrated, the press work was repeatedly performed while conveying the material to be intermittently in the longitudinal direction at a pitch of 1.2 m each time the press was calibrated. In addition, as a jig used in the press calibration method of the present invention, a combination of two jigs (jig A and jig B) as shown in Fig. 8 is selected, and the right and left bends are corrected only by jig A for comparison. Correction was also performed.

Table 2 compares the degree of left and right bending of the product after calibration by the calibration method of the present invention and the conventional calibration method. As can be seen from the results of the table, according to the press calibration method of the present invention, the bending is greatly reduced before and after calibration, whereas in the conventional press calibration method, the degree of bending is almost reduced before and after calibration, and conversely, the product width is poor. Or failure due to local deformation of the flange.

Table 1

    Full width 640 mm     Arm length 90 mm     Height 200 mm     Length 15,000mm     standard SY 295 (JIS standard)

                 Number of products: 20 each

TABLE 2

Invention calibration method Conventional Calibration Method Before correction Bending Average 20 mm 18 mm Standard deviation (σ) 2.1mm 1.8mm Other quality No problem No problem After calibration Bending Average 7 mm 16 mm Standard deviation (σ) 0.4mm 2.0mm Other quality No problem Bad shape bundle

(Example 2)

The results of applying the press calibration method according to the present invention to a general U-shaped steel pile plate having no arm portion between the joint portion and the flange portion will be illustrated below.

The dimensions of the material to be calibrated are shown in Table 3, and in this example, the press calibration of the present invention was performed to correct left and right bends that were not completely removed from the roller calibration of the previous process at both ends of the material to be calibrated (about 1.2 m each). And other treatments were the same as in Example 1.

Table 4 compares the degree of bending of the left and right products after the calibration by the calibration method of the present invention and the conventional calibration method. According to the results of the press calibration method of the present invention, the edge bending is greatly reduced before and after the calibration compared to the conventional press calibration method, and the bending correction is realized within a short time, and according to the calibration method of the present invention, it is efficiently bent. It can be seen that correction is possible.

TABLE 3

Full width 550 mm Full height 250 mm Length 12,000mm standard SY390 (JIS standard)

               Number of products: 20 each

Table 4

Calibration method of the present invention Conventional Calibration Method Before calibration Bending Average 3 mm 2 mm Standard deviation (σ) 0.5mm 0.4mm Other quality No problem No problem After calibration Bending Average 0.5mm 1.0mm Standard deviation (σ) 0.1mm 0.4mm Other quality No problem No problem Calibration time 5 minutes / piece 10 minutes / piece

(Example 3)

In this example, the roller calibration method according to the present invention is applied to a U-shaped steel pile plate having an arm part (arm) between the joint part and the flange part.

The dimensions of the material to be calibrated are shown in Table 5.

Table 5

   Full width 640 mm    Length 90 mm    Down bending 10mm / 15.3m    Length 15300 mm    standard SY 295 (JIS standard)

                 Number of products: 20 each

As a comparative example, in the case of using a conventional straightening roller in which only the web part and the flange part shown in FIG. 6 are restrained separately, as shown in FIG. 10, the web part and the flange part are simultaneously restrained by the same (integrated) roller. The cross-sectional shape after bending correction was investigated about the case where the straightening roller which concerns on this invention which arm | arm part is also restrained by the same upper and lower roller was used.

In the case of using the straightening roller according to the present invention, the inverse warping in the longitudinal direction was completely eliminated, and the cross-sectional shape and the width dimension of the arm portion were almost unchanged.

In the upper roller according to the present invention, when the web portion, the flange portion, and the arm portion are each constrained by separate rollers, the boundary portions of the web portion and the flange portion and the boundary portions of the flange and the female portion are constrained by the rollers. Because of the lack of numbers, such non-integral rollers did not have sufficient corrective effects of reverse bending.

The angle relationship of the flange part and the arm part in the longitudinal direction is shown in FIG. 14, and the relationship of the total width fluctuation amount in the longitudinal direction is shown in FIG.

FIG. 14 is a graph showing the amount of change (Δθ, angle) before and after calibration of the arm angle with respect to the longitudinal length L ₀ of the U-shaped steel pile plate. In the case of the present invention shown by the following it can be seen that almost constant regardless of the distance in the longitudinal direction. In the conventional example, it can be seen that the dark portion is deformed downward. Depending on the reduction amount and the reduction pattern at the time of calibration, the conventional example ( ), The deformation direction of the up and down direction was similar, but the same result was obtained.

FIG. 15 is a graph comparing the variation amount ΔW ₀ before and after calibration of the full width W ₀ dimension with respect to the longitudinal length L ₀ of the U-shaped steel pile plate. This is an example of the present invention, Is a comparative example, and even in this case, no actual variation is seen in the present invention.

Thus, according to this invention, compared with the conventional method, the angle of the flange part and the arm part, and the dimension of the full width have a favorable result with little change.

(Example 4)

In this example, in the same manner as in Example 3, when the calibration roller according to the present invention shown in FIG. 10 is used, and when the taper is attached to the roller shown in FIG. ), It was examined whether there was a difference in the cross-sectional shape after bending correction.

In either case, the longitudinal inverse deflection was effectively removed.

The relationship between the length L _{0 in the} longitudinal direction and the amount of change Δθ before and after the correction of the arm angle is shown in FIG. 16. The length L _{0 in the} longitudinal direction and the amount of change ΔW ₀ before and after the full width W _{0 are} shown in FIG. 16. The relationships are shown graphically in FIG. 17, respectively. From the drawing Is a case where there is no taper, "+" is a case where the roller which gave the taper was used. When the taper is not formed according to the amount of reduction and the reduction pattern during calibration ( ), The direction of deformation of the arm of the arm is shown to be upside down, but the same result is obtained.

From these results, it can be seen that both the angular fluctuation amount and the fluctuation amount of the overall width of the arm portion are reduced by giving a taper.

As is apparent from the above embodiment, when the press calibration method and the calibration jig of the present invention are used, the U-shaped steel plate can be efficiently calibrated in a short time, and in particular, the lateral bending stiffness such as the U-shaped steel plate having the arm portion. Even with this large short-lived steel pile plate, effective press calibration is possible without product defects, and its industrial use value is very large.

Further, in the roller calibration of the U-shaped steel pile plate having the arm portion using the straightening roller of the present invention, the roller calibration can be performed without changing the cross-sectional shape (total width, angle of the flange portion and the arm portion).

MEANS TO SOLVE THE PROBLEM This inventor easily press-corrects the bending of the steel pile board with the big bending rigidity of a product lateral direction. In addition to pressing one flange outer surface, it presses the other inner surface of a flange simultaneously in the same direction, and also the arm part is pressed. In the roller calibration of the reverse bending of the excitation U-shaped steel pile plate, it has been found that the upper and lower parts of the rollers that restrain the web portion, the flange portion, and the arm portion can be vertically and accurately corrected.

To this end, the present invention provides both a first jig having a surface for pressing the outer surface of one flange of the U-shaped steel pile plate, and a second jig connected with the corresponding first jig and pressing the inner surface of the other flange. It provides a calibration jig of a U-shaped steel pile plate, characterized in that made in combination, through which the steel plate with a large bending stiffness in the product direction, such as a U-shaped steel pile plate having a female portion between the flange and the joint By providing a calibration method capable of efficiently correcting bending, it is possible to easily press-bend the bending of the steel pile plate having the large bending stiffness in the product lateral direction described above, and to obtain the effect of precisely correcting the arm portion.

BRIEF DESCRIPTION OF THE DRAWINGS It is typical explanatory drawing of the reverse bending of a steel pile plate.

2 is a schematic explanatory diagram of bending of a steel pile plate.

3 is a schematic explanatory diagram of a press calibration method for bending a steel pile plate.

4 (a) is explanatory drawing of the reduction in the press calibration of the steel pile plate,

4 (b) is an explanatory view of the flange local deformation.

5 is an explanatory diagram of a conventional roller calibration method in the U-shaped steel pile plate.

6 is an explanatory diagram of a conventional roller calibration method for a U-shaped steel pile plate having an arm portion.

7 is an explanatory diagram of a press calibration method according to the present invention.

8 is an explanatory diagram showing an example of a press calibration jig according to the present invention.

9 is an explanatory view of another embodiment of a press calibration jig according to the present invention.

10 is an explanatory view of an arrangement example of a U-shaped steel pile plate having a female part and a straightening roller according to the present invention.

11 (a) and 11 (b) are explanatory views of the upper and lower straightening rollers according to the present invention of the U-shaped steel pile plate having arm portions.

12 is an explanatory view of a cross-sectional shape of the U-shaped steel pile plate at the time of upper roller calibration.

Fig. 13 is an explanatory view of the cross-sectional shape of the U-shaped steel pile plate at the time of lower roller calibration.

14 is a graph showing the angular relationship between the flange portion and the arm portion in the longitudinal direction.

Fig. 15 is a graph showing the total width variation in the longitudinal direction.

Fig. 16 is a graph showing the angular relationship between the flange portion and the arm portion in the longitudinal direction.

Fig. 17 is a graph showing the total width variation in the longitudinal direction.

Claims (6)

In the roller straightening method of a U-shaped steel pile plate having a web portion, a flange portion, and a joint portion, and having an arm portion between the joint portion and the flange portion, the arm portion is added in the vertical direction in addition to the web portion and the flange portion. A roller calibration method for a U-shaped steel pile plate with an arm portion, characterized by using a straightening roller which restrains from the. 2. The roller straightening method according to claim 1, wherein the straightening roller that constrains the arm portion from the up-down direction in addition to the web portion and the flange portion is composed of integral rollers. The roller calibration method according to claim 1, wherein the upper and lower straightening rollers are arranged in a zigzag shape up and down. 4. The roller calibration according to claim 3, wherein when restraining the arm portion between the flange portion and the joint portion, the arm portion using a straightening roller which restrains from the up and down direction by giving an angle different from the product cross section. Way. 5. The roller straightening method according to claim 4, wherein the straightening roller that constrains the arm portion from the up and down direction in addition to the web portion and the flange portion is composed of rollers each of the upper and lower parts of the integral type. delete