JP4854886B2 - H-section steel excellent in straightness and toughness and its straightening method - Google Patents

Description

【００４０】
以上は、図６のＨ形鋼圧延矯正工程の場合であるが、本発明の技術は熱間矯正、温間矯正、冷間矯正など幅広い工程に適用可能である。
【００４１】
【発明の効果】
本発明は、均一変形性に優れた圧延矯正方法と、不均一変形ではあるが形状制御性の良い曲げ矯正方法とを適切に組み合わせて、両者の欠点を補うとともに、その長所を十分発揮させるようにしたことにより、従来の矯正方法では達成が極めて困難な真直で靭性に優れるＨ形鋼を製造することが可能となった。
【００４２】
本発明は、Ｈ形鋼の形状、材質に制限されることなく、各種のＨ形鋼に適用することが可能であり、いずれも耐久性、真直性に優れたＨ形鋼を得ることができる。
【図面の簡単な説明】
【図１】Ｈ形鋼の長手方向に直角な断面を示す図であり、図１（ａ）は本発明のＨ形鋼、図１（ｂ）は従来技術のＨ形鋼の場合をそれぞれ示す。
【図２】本発明の矯正方法における矯正装置の基本構成を示す図である。
【図３】本発明の技術に関するＨ形鋼と圧延機のロールとの位置関係を示す垂直断面図である。
【図４】従来技術と本発明の技術の矯正特性を比較するモデルを示す図であり、図４（ａ）はローラーレベラーの、図４（ｂ）は本発明の技術におけるモデルをそれぞれ示す。
【図５】図４のモデルにより求めた矯正反力と圧延圧下率との関係を示す図である。
【図６】Ｈ形鋼の圧延および矯正工程を示す図である。
【図７】従来の矯正技術を示す図である。
【図８】従来の矯正技術を示す図であり、図８（ａ）は上ロールの、図８（ｂ）は下ロールの図を示す。
【図９】従来の矯正技術により矯正されたＨ形鋼を示す図であり、図９（ａ）は凹み疵、図９（ｂ）は割れ疵の発生状況をそれぞれ示す図である。
【図１０】従来の矯正技術を示す図である。
【符号の説明】
１…Ｈ形鋼
２，２ａ，２ｂ…ローラーレベラーの矯正ロール
３，３’…ウエブ矯正用ロール
４，４’…フランジ先端矯正用ロール
６…被矯正材（Ｈ形鋼）
５０…Ｈ形鋼
５１…ユニバーサル圧延機
５２…入側ピンチロール列
５３…出側ピンチロール列
５４，５４’…ユニバーサル圧延機の水平ロール
５５，５５’…ユニバーサル圧延機の竪ロール
５６，５６’…入側ピンチロール列の水平ピンチロール
５７，５７’…入側ピンチロール列の竪ピンチロール
５８，５８’…出側ピンチロール列の水平ピンチロール
５９，５９’…出側ピンチロール列の竪ピンチロール
６１…Ｈ形鋼のウエブ
６２，６２’…Ｈ形鋼のフランジ
６４…ウエブとフランジとの接続部近傍の凹み疵
６５…ウエブとフランジとの接続部近傍の割れ疵
７１，７２，７３…ローラーレベラーの矯正ロール[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an H-section steel, and more particularly to an H-section steel having uniform mechanical properties throughout the material and excellent in strength and toughness and a method for correcting the same.
[0002]
[Prior art]
In recent years, high-rise buildings have been oriented mainly in urban areas where population density is high, and accordingly, development of building structures and steel materials with excellent earthquake resistance are required in consideration of safety in the event of an earthquake. .
[0003]
Against this background, mechanical properties such as the strength of the H-shaped steel used in the framework of the steel structure of high-rise buildings are important factors in determining the earthquake resistance of building steel structures. .
[0004]
Shaped steel products such as H-section steel have a complicated cross-sectional shape, so when hot-rolling it, the rolling or cooling conditions differ depending on the part, and the structure and mechanical properties may vary. is there.
[0005]
In addition, in the manufacturing technology of shape steel such as H-section steel, securing dimensional accuracy and straightness of each part in the longitudinal direction is an important issue. To obtain a shaped steel product with high dimensional accuracy and straightness Since there is a limit to manufacturing only by hot rolling, usually, after rolling, the rolled material is further corrected cold or warm to ensure high dimensional accuracy and straightness of the shaped steel product. However, in the past, particularly in the method of straightening H-section steel, the following local mechanical characteristics are likely to be deteriorated due to the cross-sectional shape, and this has been a factor that deteriorates the earthquake resistance.
[0006]
As shown in FIG. 7, a conventional straightening method for H-section steel is staggered vertically or horizontally along a pass line (conveying direction of the section steel) as shown in Japanese Patent Application Laid-Open No. 50-125851. In addition, by using a roller leveler provided with the straightening rolls 2 and adjusting the pushing position of each straightening roll with respect to the pass line so that the curvature of bending decreases as the latter stage, the material to be straightened (H-shaped steel) ) The method of correcting by repeating bending of 6 was common.
[0007]
This straightening method using a roller leveler is a relatively compact facility, and once it is set to appropriate conditions, it is easy to introduce because unattended operation is possible, but it has the following problems.
[0008]
That is, in the correction method disclosed in Japanese Patent Application Laid-Open No. 50-125851, the correction rolls 2a and 2b shown in FIGS. 8 (a) and 8 (b) are arranged in an H shape that is a material to be corrected. It is to correct the vertical bending of the shape steel by directly pushing the two locations near the flanges 62 and 62 'of the web portion 61 of the steel 6 in the direction approaching the path line of the shape steel from either the upper side or the lower side. is there. At that time, assuming that the load of the straightening rolls 2a and 2b is P, P / 2 is provided at two locations in the vicinity of the connecting portion (corner portion, region indicated by ○) between the web 61 of the H-section steel 6 and the flanges 62 and 62 ′. Each load is loaded and acts as a shear stress.
[0009]
When the shear stress acting in the vicinity of the connection portion between the web 61 and the flanges 62 and 62 ′ increases until it exceeds the yield stress of the H-section steel 6, shear plastic strain occurs and the hardness increases at room temperature (working) Hardened) and tend to be brittle compared to other parts, resulting in a decrease in toughness.
[0010]
On the other hand, in recent years, the local work hardening in the vicinity of the connecting portion (corner portion) between the web portion and the flange portion in the straightening of the H-shaped steel due to the thinning of the web accompanying the weight reduction of the H-shaped steel. And the toughness fall resulting from it tends to occur easily, and is a factor that deteriorates the earthquake resistance of the H steel shape used for the steel structure for construction. Further, in the case of correcting under more severe conditions by such a correction method, as shown in FIGS. 9 (a) and 9 (b), in the vicinity of the connecting portion between the web portion of the shape steel and the flange portion (corner) There is also a problem that a dent 64 (FIG. 9A) is generated in the portion or a crack 65 (FIG. 9B) is likely to be generated.
[0011]
In order to improve the above problem, Japanese Patent Laid-Open No. 52-50958 discloses a straightening device in which a plurality of upper rolls and lower rolls are alternately arranged as shown in FIG. It consists of straightening rolls 3 and 3 'and flange tip straightening rolls 4 and 4', and the straightening machine shaft with the web straightening rolls 3 and 3 'mounted at a distance from each other has an inner diameter larger than the straightening machine axis. Flange tip straightening rolls 4 and 4 ′ arranged so as to obtain an appropriate interval between the straightening machine shafts are rotatably mounted via a collar (not shown) having rotation transmission teeth, and the flange tip On the back of the straightening rolls 4 and 4 ', an H-shaped steel straightening device is disclosed, which is provided with a backup roll device for rolling down the flange tip via a backup roll (not shown), H type 6, the ends of the flanges 62, 62 ′ are pressed down from the same direction following the dimensional variation of the H-section steel 6. It is disclosed that the shear stress at the corner portion between the web portion 61 and the flanges 62 and 62 ′ is reduced, and local cracks and dents and material deterioration due to the shear stress are prevented.
[0012]
However, in the method and apparatus disclosed in Japanese Patent Laid-Open No. 52-50958, a complicated apparatus in which a backup roll apparatus is attached to a plurality of straightening rolls (usually 7 or more) constituting a roller leveler is required. There are problems that maintenance costs increase and it is difficult to adjust complicated backup rolls.
[0013]
[Problems to be solved by the invention]
As described above, in the conventional method of correcting the H-shaped steel with the roller leveler, shear plastic strain is generated in the vicinity of the connection portion (corner portion) between the web portion and the flange portion of the H-shaped steel in order to use the repeated bending action. Concentration has a problem that work hardening and toughness deterioration due to the work tend to occur.
[0014]
H which reduces the concentration of shear plastic strain in the vicinity of the connecting portion (corner portion) between the web portion and the flange portion by simultaneously reducing the web portion and the flange portion of the H-section steel disclosed in JP-A-52-50958. The straightening method using a roller leveler for shape steel is effective under certain conditions, but it is used to straighten H-section steel with a reduced web thickness for weight reduction and H-section steel with strict requirements for straightness. However, the effect was not sufficient, and there was a problem of work hardening due to the concentration of shear plastic strain in the vicinity of the connection portion (corner portion) between the web portion and the flange portion, and toughness deterioration resulting therefrom.
[0015]
In view of these problems of the prior art, the present invention is superior in straightness in the entire length in the longitudinal direction to replace the straightening method using the repeated bending action by the conventional roller leveler, and is uniform in a straight section perpendicular to the longitudinal direction. Of straightening and toughness in the longitudinal length and the straightening method and the straightening method of the H-shaped steel with a long strain history and no toughness deterioration due to local work hardening The purpose is to do.
[0016]
[Means for Solving the Problems]
The present invention solves the above technical problems, and the gist thereof is as follows.
(1) An H-section steel having excellent straightness and toughness , which is 10% or less using a rolling mill capable of plastically deforming the entire cross section perpendicular to the longitudinal direction of the H-section steel in the straightening process after rolling. With the draw ratio, the entire cross-section is uniformly reduced so as to be plastically deformed, and the pinch roll provided on one or both of the exit side and the entrance side of the rolling mill is used to deform the H-section steel being plastically deformed. In the cross section perpendicular to the longitudinal direction of the H-shaped steel after straightening, which is straightened by applying a bending moment, the material hardness in the vicinity of the connection between the flange of the H-shaped steel and the web is An H-section steel excellent in straightness and toughness, characterized in that the average hardness of a cross section perpendicular to the direction is 1.2 times or less.
(2) An H-section steel excellent in straightness and toughness, using a rolling mill capable of plastically deforming the entire cross section perpendicular to the longitudinal direction of the H-section steel in the straightening process after rolling,
With a stretching ratio of 10% or less, while uniformly rolling down the entire cross section so as to be plastically deformed,
The pinch roll provided on either or both of the outlet side and the inlet side of the rolling mill was corrected by applying a bending moment and a longitudinal tension to the H-shaped steel during plastic deformation,
Within the cross section perpendicular to the longitudinal direction of the H-shaped steel after straightening, the material hardness in the vicinity of the connection portion between the flange and the web of the H-shaped steel is 1. 2 times or less
H-section steel with excellent straightness and toughness.
( 3 ) A method for straightening H-section steel having excellent straightness and toughness,
Using a rolling mill that can plastically deform the entire cross section perpendicular to the longitudinal direction of the H-shaped steel in the straightening process after rolling,
With a stretching ratio of 10% or less, while uniformly rolling down the entire cross section so as to be plastically deformed,
H-shape excellent in straightness and toughness, characterized in that a bending moment is applied to the H-shaped steel during plastic deformation by a pinch roll provided on either or both of the exit side and the entry side of the rolling mill Steel straightening method.
( 4 ) A method for correcting H-section steel having excellent straightness and toughness,
Using a rolling mill that can plastically deform the entire cross section perpendicular to the longitudinal direction of the H-shaped steel in the straightening process after rolling,
With a stretching ratio of 10% or less, while uniformly rolling down the entire cross section so as to be plastically deformed,
Straightness characterized by applying a bending moment and a longitudinal tension to the H-shaped steel during plastic deformation by a pinch roll provided on one or both of the exit side and the entrance side of the rolling mill And straightening method of H-section steel excellent in toughness.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below.
[0018]
FIG. 1 is a diagram showing the hardness distribution of a cross section perpendicular to the longitudinal direction of an H-section steel, where (a) is the H-section steel of the present invention, and (b) is H after the roller leveler correction, which is a prior art. This is the case of shape steel. In the following, the section refers to a section perpendicular to the longitudinal direction of the H-section steel. As shown in FIG. 1 (b), the hardness of the material in the vicinity of the connection portion between the flange of the H-section steel and the web where the strain is locally concentrated by the roller leveler correction is larger than the average hardness of the cross section perpendicular to the longitudinal direction. And an area exceeding 1.2 times the average hardness exists through the web thickness. Further, within that region, the hardness in the region near the web surface reaches 1.4 times or more of the average hardness. When this H-shaped steel was subjected to an earthquake resistance test in a low temperature environment, it was found that brittle fracture was likely to occur starting from the most hardened part of the web surface.
[0019]
In general, the strength of a metal material such as steel increases due to work hardening, and conversely, ductility decreases. The inventors conducted mechanical property tests on various materials that were partially work-hardened, and as shown in FIG. 1 (a), in the vicinity of the connection between the hardened portion, the flange of the H-shaped steel and the web (see FIG. 1 (a) circled region) is less than 1.2 times the average hardness in the cross section perpendicular to the longitudinal direction, the ductility is less deteriorated, and 1.1 times or less is practically It was found that local ductility reduction is not a problem. That is, according to the present invention, the hardness of the material in the vicinity of the connecting portion between the flange of the H-shaped steel and the web, at least the material hardness in the vicinity of the connecting portion on the web side, in the cross section perpendicular to the longitudinal direction of the straight H-shaped steel. The average hardness of the cross section perpendicular to the longitudinal direction of the H-shaped steel is 1.2 times or less. Furthermore, the present invention makes it possible to produce an H-section steel having a hardness distribution shown in FIG. 1 (a) by a correction method characterized by light reduction. That is, in a straightening process after rolling, a rolling mill capable of plastically deforming the entire cross section perpendicular to the longitudinal direction of the H-section steel is reduced at a drawing rate of 10% or less, and the outlet side and the inlet side of the rolling mill are A predetermined bending moment and a longitudinal tension are applied to the H-shaped steel during plastic deformation by a pinch roll provided on one or both of them. By this correction, the average material hardness in the cross section perpendicular to the longitudinal direction of the H-shaped steel is obtained by calculating the material hardness in the vicinity of the connection between the flange of the H-shaped steel and the web in the cross section perpendicular to the longitudinal direction of the H-shaped steel after the straightening. The hardness can be 1.2 times or less.
[0020]
FIG. 2 is a diagram showing the basic configuration of the equipment used in the method for straightening the H-section steel of the present invention. The H-section steel 50 formed into a predetermined cross-sectional dimension in the rolling process is an entry-side free pinch roll row 52. And the situation which has passed the universal rolling mill 51 and the exit side free pinch roll row | line | column 53 is shown.
[0021]
FIG. 3 is a vertical sectional view showing the positional relationship between the H-section steel being rolled in FIG. 2 and the rolls of the rolling mill. The H-section steel 50 is sandwiched between the upper and lower horizontal rolls 54 and 54 ′ and the left and right vertical rolls 55 and 55 ′ of the universal rolling mill 51, and the entire cross section is simultaneously pressed down, so that the entire cross section is plastically deformed. The H-shaped steel is straightened to a predetermined cross-sectional dimension. At that time, since the horizontal roll is a system in which the H-shaped steel web is sandwiched from above and below, the rolling load applied from each horizontal roll to the H-shaped steel is offset by balancing the web in the vertical direction. Therefore, the shear force does not act in the vicinity of the connection portion between the web and the flange, and there are no problems such as generation of local shear strain and deterioration of the material. Thus, a straightening device using a universal rolling mill as a rolling mill capable of plastically deforming the entire cross section of the H-section steel is extremely useful.
[0022]
In addition, the straightening rolling stretch rate is defined as 10% or less, and by setting the stretch rate to 10% or less, it is possible to sufficiently suppress an increase in the hardness in the vicinity of the joint between the flange and the web during straightening. , This can be less than 1.2 times the average hardness of the cross section perpendicular to the longitudinal direction, and if the elongation beyond this, the change in the cross-sectional shape of the H-shaped steel is large, it is difficult to control the target shape This is because the rolling reaction force increases, the apparatus becomes larger, and the equipment cost increases.
[0023]
FIG. 4 is a model diagram introduced in order to compare the deformation characteristics of the H-shaped steel by the correction by the conventional roller leveler and the correction of the present invention. FIG. 4A is a diagram showing a part of the H-shaped steel and the straightening roll in the conventional roller leveler straightening. The points B ′, A and B are the straightening rolls 72, 71 and 73 and the H-shaped steel, respectively. The point B is set at a position where the H-section steel 50 is pushed in by the pushing amount Δ. Therefore, since the H-section steel 50 is subjected to downward convex bending correction, a correction reaction force is generated at point B.
[0024]
FIG. 4 (b) is a view showing the H-section steel and roll in the straightening according to the present invention, and B ′ and B points are input side pinch rolls 57 ′, 57 and output side pinch rolls 59 ′, 59 and H, respectively. The points A and A ′ correspond to the contact portions between the rolls 55 and 55 ′ of the universal rolling mill and the H-section steel 50. Also in this case, the point B is set to a position where the H-section steel 50 is pushed by the pushing amount Δ. Therefore, since the H-section steel 50 is subjected to downward convex bending correction, a correction reaction force is generated at point B. At that time, since the H-section steel 50 is rolled by the rolling amount u by the rolls 55 and 55 ′, the reaction force at the point B also changes as the rolling amount u changes. Further, since the pinch rolls 57, 57 ′ or 59, 59 ′ are driven to rotate and pull the H-section steel 50, tension acts in the longitudinal direction of the H-section steel in the vicinity of A and A ′ where the correction effect occurs (FIG. 4). (The direction of the left and right arrows in (b)). In this way, a predetermined bending moment and further a longitudinal tension can be applied to the H-shaped steel during plastic deformation. It should be noted that the required bending moment and the longitudinal tension applied for correction can be set in consideration of the deformation state of the H-shaped steel as the material to be corrected, the stretch ratio, and the like. The larger the tension to be loaded, the better the effect of reducing the springback. However, an excessively large tension load increases the equipment cost of the pinch roll, so it is necessary to set it considering its cost effectiveness. In general, if a tension of about 10% of the deformation resistance of the shape steel can be applied, a remarkable effect is recognized.
[0025]
FIG. 5 is a diagram comparing the correction reaction force between the roller leveler correction and the compulsion of the present invention as a result obtained by the elasto-plastic finite element analysis with respect to the model of FIG. The vertical axis represents the reaction force acting on point B of the pinch roll by correction in FIGS. 4A and 4B, and the horizontal axis represents the rolling reduction rate at points A and A ′. When the horizontal axis is 0, since bending correction is performed without rolling, this corresponds to FIG. 4A, and in this case, the correction reaction force becomes the maximum value. Further, the straightening reaction force monotonously decreases as the rolling reduction in rolling increases. This is because the cross section of the H-shaped steel including the material in the roll bite which has already yielded due to the reduction of the straight rolling in FIG. 4B, that is, the point A and the point A ′ (the cross section perpendicular to the longitudinal direction of the section steel). ) Since the bending stress resulting from the reaction force of the pinch roll 59 'is superimposed on the nearby material, the reaction force at point B decreases as the yield zone increases due to an increase in rolling reduction. Understood. Furthermore, since the yield due to the tension applied by the pinch rolls is further increased, the correction reaction force at the point B decreases as shown by the arrow in FIG. The technique of the present invention, the residual stress due to correction in comparison with the prior art can be reduced, significantly reduced the amount of spring back due to unloading after矯positive, it is possible to correct with high accuracy.
[0026]
From the above, it is possible to produce an H-section steel that is straight and excellent in strength and toughness.
[0027]
FIG. 2 shows an embodiment of a straightening device used in the straightening method of the present invention. On the entry side and the exit side of the universal rolling mill 51, the vertical and horizontal movements with respect to the feed direction of the H-section steel, It has a basic configuration in which free pinch roll rows 52 and 53 that can be positioned up and down, left and right, and inclined by rotation of a clock and a counterclockwise shaft are arranged. By positioning the pinch roll, a required bending moment can be given to the H-shaped steel during plastic deformation. The movement of the pinch roll, the rotation of the shaft, and the like can be performed by appropriately providing a hydraulic or electric actuator or the like. With respect to the free pinch roll row, either the entry side or the exit side may be used, but at least one pair of pinch rolls in the pinch roll row is driven to rotate. By this rotational driving, a longitudinal tension can be further applied to the H-shaped steel that is being plastically deformed between the rolling mill and the pinch roll. The tension can be adjusted by controlling the rotational drive of the pinch roll. In addition, by adjusting the tension to be applied by increasing the rolling force of the pinch roll or increasing the number of pinch rolls for controlling the rotational speed to ensure the frictional force between the pinch roll and the H-section steel. Is also preferable.
[0028]
【Example】
FIG. 6 is a diagram showing a process of manufacturing H-shaped steel by rolling and straightening a material.
[0029]
The straightening device shown in FIG. 2 was replaced with a roller leveler straightening machine in a general H-shaped steel rolling straightening process shown in FIG. 6, and the capabilities of the two were compared under the conditions shown in Table 1. Table 1 shows the evaluation results regarding various characteristics.
[0030]
First, in the roller leveler straightening machine, the bending of the H-section steel steady part could be corrected with the basic setting that the roll push-in amount was large on the entry side and decreased as it went to the exit side. However, with regard to the end of the H-section steel, a case where it was out of tolerance was observed with considerable frequency. These out-of-tolerance H-shaped steels had to be remedied by correcting them with a press machine with extremely low productivity, or by cutting and removing the end portions on the premise of yield loss.
[0031]
Also, the overall length of the H-shaped steel after straightening the roller leveler, especially the part that has undergone press straightening, has a tolerance that changes when the H-shaped steel is cut at right angles to the longitudinal direction and the cross-sectional shape changes near the cut surface due to the springback. The case where it deviates from was observed.
[0032]
Further, the straightened H-section steel was cut at a plurality of positions at right angles to the longitudinal direction, and the Vickers hardness distribution in the cross section was measured. As a result, as shown in FIG.1 (b), it turned out that the hardness of the connection part vicinity of a web and a flange is large compared with another part. In particular, in the H-section steel having a large size and a small web thickness, the increase in the hardness of the portion was remarkable, and therefore, there was a case where the ductility was insufficient locally.
[0033]
Furthermore, with regard to straightness, it has been found that the bending of the front and rear ends is not corrected.
[0034]
This is unavoidable because of the principle of roller leveler correction, since the correction moment does not act on the front and rear ends of the straightening rolls.
[0035]
On the other hand, in the method of the present invention, it has been found that, in the examples shown in Table 1, the target tolerance including the both ends of the H-section steel is substantially within the target tolerance. Moreover, even if it cut | disconnected at right angles to the longitudinal direction in any place including the edge part of H-section steel, the big change of the cross-sectional shape was not seen. Furthermore, it was confirmed that it is possible to correct a torsional defect that is difficult to correct with a roller leveler.
[0036]
Moreover, although the hardness distribution of the cross section cut at a plurality of positions perpendicular to the longitudinal direction was measured, in any case, as shown in FIG. 1 (a), the material hardness in the vicinity of the connection portion between the flange and the web is The average hardness of the cross section of the H-shaped steel was 1.2 times or less, and no significant difference in hardness was observed. For this reason, the target for ductility was also satisfied.
[0037]
Furthermore, with regard to straightness, it has been found that the straightness is good over the entire length, and the product is used as it is.
[0038]
From the above results, it has been found that the method of the present invention can completely replace the conventional roller leveler with dimensional accuracy. In addition, it was confirmed that it is possible to correct a twisting defect that is difficult to correct with a roller leveler.
[0039]
[Table 1]

[0040]
The above is the case of the H-shaped steel rolling straightening process of FIG. 6, but the technique of the present invention can be applied to a wide range of processes such as hot straightening, warm straightening, and cold straightening.
[0041]
【The invention's effect】
The present invention appropriately combines a rolling straightening method with excellent uniform deformability and a bending straightening method with non-uniform deformation but good shape controllability to make up for the disadvantages of both, and to fully demonstrate its advantages. As a result, it has become possible to produce a straight H-shaped steel with excellent toughness that is extremely difficult to achieve with conventional straightening methods.
[0042]
The present invention is not limited to the shape and material of the H-shaped steel, and can be applied to various H-shaped steels, and any H-shaped steel excellent in durability and straightness can be obtained. .
[Brief description of the drawings]
FIG. 1 is a view showing a cross section perpendicular to the longitudinal direction of an H-section steel, FIG. 1 (a) shows the case of the H-section steel of the present invention, and FIG. .
FIG. 2 is a diagram showing a basic configuration of a correction device in the correction method of the present invention.
FIG. 3 is a vertical sectional view showing a positional relationship between an H-section steel and a roll of a rolling mill related to the technique of the present invention.
FIG. 4 is a diagram showing a model for comparing the correction characteristics of the prior art and the technology of the present invention, FIG. 4 (a) shows a roller leveler, and FIG. 4 (b) shows a model in the technology of the present invention.
5 is a diagram showing the relationship between the correction reaction force obtained from the model of FIG. 4 and the rolling reduction ratio. FIG.
FIG. 6 is a diagram showing a rolling and straightening process of H-section steel.
FIG. 7 is a diagram showing a conventional correction technique.
8A and 8B are diagrams showing a conventional straightening technique, in which FIG. 8A shows an upper roll, and FIG. 8B shows a lower roll.
FIG. 9 is a view showing an H-shaped steel straightened by a conventional straightening technique, FIG. 9 (a) is a view showing the state of occurrence of dent flaws, and FIG.
FIG. 10 is a diagram showing a conventional correction technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... H-section steel 2, 2a, 2b ... Roller leveler straightening roll 3, 3 '... Web straightening roll 4, 4' ... Flange tip straightening roll 6 ... Material to be straightened (H-shaped steel)
DESCRIPTION OF SYMBOLS 50 ... H-section steel 51 ... Universal rolling mill 52 ... Entrance side pinch roll row | line | column 53 ... Outlet side pinch roll row | line | column 54, 54 '... Horizontal roll 55, 55' of a universal rolling mill ... Roll roll 56, 56 'of a universal rolling mill ... Horizontal pinch rolls 57 and 57 'in the entry side pinch roll row ... Pinch rolls 58 and 58' in the entry side pinch roll row Horizontal pinch rolls 59 and 59 'in the exit side pinch roll row ... Pinch roll 61 ... H-shaped steel web 62, 62 '... H-shaped steel flange 64 ... Recessed flange 65 in the vicinity of the connecting portion between the web and the flange 65 ... Cracking rod 71, 72, 73 in the vicinity of the connecting portion between the web and the flange ... Roller leveler straightening roll

Claims (4)

H-section steel with excellent straightness and toughness,
Using a rolling mill that can plastically deform the entire cross section perpendicular to the longitudinal direction of the H-shaped steel in the straightening process after rolling,
With a stretching ratio of 10% or less, while uniformly rolling down the entire cross section so as to be plastically deformed,
The pinch roll provided on either or both of the outlet side and the inlet side of the rolling mill was corrected by applying a bending moment to the H-shaped steel during plastic deformation,
Within the cross section perpendicular to the longitudinal direction of the H-shaped steel after straightening, the material hardness in the vicinity of the connection portion between the flange and the web of the H-shaped steel is 1. An H-section steel excellent in straightness and toughness, characterized by being twice or less. H-section steel with excellent straightness and toughness,
Using a rolling mill that can plastically deform the entire cross section perpendicular to the longitudinal direction of the H-shaped steel in the straightening process after rolling,
With a stretching ratio of 10% or less, while uniformly rolling down the entire cross section so as to be plastically deformed,
The pinch roll provided on either or both of the outlet side and the inlet side of the rolling mill was corrected by applying a bending moment and a longitudinal tension to the H-shaped steel during plastic deformation,
Within the cross section perpendicular to the longitudinal direction of the H-shaped steel after straightening, the material hardness in the vicinity of the connection portion between the flange and the web of the H-shaped steel is 1. An H-section steel excellent in straightness and toughness, characterized by being twice or less. A straightening and toughness correcting method for H-section steel,
Using a rolling mill that can plastically deform the entire cross section perpendicular to the longitudinal direction of the H-shaped steel in the straightening process after rolling,
With a stretching ratio of 10% or less, while uniformly rolling down the entire cross section so as to be plastically deformed,
H-shape excellent in straightness and toughness, characterized in that a bending moment is applied to the H-shaped steel during plastic deformation by a pinch roll provided on either or both of the exit side and the entry side of the rolling mill Steel straightening method. A straightening and toughness correcting method for H-section steel,
Using a rolling mill that can plastically deform the entire cross section perpendicular to the longitudinal direction of the H-shaped steel in the straightening process after rolling,
With a stretching ratio of 10% or less, while uniformly rolling down the entire cross section so as to be plastically deformed,
Straightness characterized by applying a bending moment and a longitudinal tension to the H-shaped steel during plastic deformation by a pinch roll provided on one or both of the exit side and the entrance side of the rolling mill And straightening method of H-section steel excellent in toughness.

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