Patent Application
20200078842
This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2017-102423, filed in Japan on May 24, 2017, the entire contents of which are incorporated herein by reference.
The present invention relates to a production method for producing H-shaped steel using, for example, a slab having a rectangular cross section or the like as a raw material.
In the case of producing H-shaped steel, a raw material such as a slab or a bloom extracted from a heating furnace is shaped into a raw blank (a material to be rolled in a so-called dog-bone shape) by a rough rolling mill (BD). A web and flanges of the raw blank are subjected to reduction in thickness by an intermediate universal rolling mill, and flanges of the material to be rolled are subjected to width reduction and forging and shaping of end surfaces by an edger rolling mill close to the intermediate universal rolling mill. Then, an H-shaped steel product is shaped by a finishing universal rolling mill.
In such a method for producing H-shaped steel, for shaping the raw blank in the so-called dog-bone shape from the slab raw material having a rectangular cross section, there is a known technique of creating splits on slab end surfaces in a first caliber at a rough rolling step, then widening the splits or making the splits deeper in second and subsequent calibers, and eliminating the splits on the slab end surfaces in calibers subsequent thereto.
Besides, in production of the H-shaped steel, it is known that after so-called edging rolling of edging the end surfaces of the raw material such as a slab (slab end surfaces), flat shaping and rolling is performed in which the material to be rolled is rotated by 90° or 270° and reduction of a web corresponding part is performed. In this flat shaping and rolling, a flange corresponding part is subjected to reduction and shaping together with the reduction of the web corresponding part.
Incidentally, in recent years, an H-shaped steel product with a larger size is required. Accordingly, it is studied to produce an H-shaped steel product from a slab raw material with a size larger than a conventional one. Here, in general flat shaping and rolling, when a large-size raw material is used as a material to be rolled, various problems such as elongation in a web height direction and deformation of the flange corresponding part may arise, and correction of the shape is sometimes required. Concretely, there is a concern about a phenomenon that with the reduction of the web corresponding part, the web corresponding part elongates in the longitudinal direction and the flange corresponding part also elongates in the longitudinal direction by being drawn by the elongation of the web corresponding part, resulting in a decrease in thickness of the flange corresponding part.
Regarding the flat shaping and rolling as above, for example, Patent Document 1 discloses a technique in which groove parts are formed on a middle part of a flat shaping caliber, and an unreduced portion is provided at the middle of a web corresponding part when performing rolling, thereby reducing a length of a crop part. This Patent Document 1 describes that edging rolling is performed in a state where a protruding part (corresponding to a raised part of the present invention) is formed at the middle of the web corresponding part, and further reduction in the crop part and efficiency of the rolling are realized.
Further, for example, Patent Document 2 discloses a width-widening rolling method for performing shaping processing in an advantageous manner on shaped blooms in a production process of shape steel. Concretely, this Patent Document 2 discloses a rolling method in which local rolling is performed on a web corresponding part, rolling for flattening a protruding part at the middle of the web corresponding part and widening a width is then performed, and after that, a material to be rolled is erected and subjected to edging rolling. It is described that according to this method, a lot of kinds of shaped blooms can be produced by adjusting a flange width, a web thickness, and a web height.
As described above, recently, with an increase in size of structures and the like, production of a large-size H-shaped steel product is desired. In particular, a product having flanges, which greatly contribute to strength and rigidity of H-shaped steel, made wider as compared with conventional ones is desired. To produce the H-shaped steel product with widened flanges, it is necessary to shape a material to be rolled with a flange width larger as compared with a conventional one from the shaping at the rough rolling step.
In production of an H-shaped steel product, it is conventionally known to perform light reduction rolling by returning a material to be rolled to an edging caliber after flat shaping and rolling, in order to prevent an overfill at a position of a flange outer surface when performing the flat shaping and rolling. This light reduction rolling can be referred to as so-called supplementary ranked edging rolling. In the present description, this is referred to as “supplementary edging process” or simply referred to as “supplementary edging rolling”. In this supplementary edging rolling, web thickness reduction and reduction in a flange width direction are performed by flat shaping and rolling, and then the material to be rolled is returned to the edging caliber, so that the material to be rolled whose flange width is shortened does not fill the edging caliber, and thus deterioration of a material passing property and deterioration of a shape of the material to be rolled are concerned. The deterioration of the material passing property and the deterioration of the shape of the material to be rolled when performing the supplementary edging rolling as described above may become more significant when the material to be rolled has a large size and when producing an H-shaped steel product with a large web height, in particular.
The technique disclosed in the aforementioned Patent Document 1 is a technique of reducing the length of the crop part, Patent Document 1 does not disclose at all the technical idea such that a material to be rolled with a large flange width is shaped, and does not mention at all the performance of the above-described “supplementary edging rolling”, and the deterioration of the material passing property and the deterioration of the shape of the material to be rolled which become problems when performing the supplementary edging rolling. Further, in the technique disclosed in the aforementioned Patent Document 2 in which the protruding part is formed at the middle of the web corresponding part, the rolling for flattening the protruding part at the middle of the web corresponding part and widening the width is then performed, and after that, the material to be rolled is erected and subjected to the edging rolling, a step of flattening the protruding part every time the protruding part is formed at the middle of the web corresponding part, is employed, so that the increase in the number of times of movement of the material to be rolled between calibers is concerned. In particular, when the above “supplementary edging rolling” is performed plural times, the increase in the number of times of movement between calibers becomes significant and a rolling efficiency is lowered, which is a problem.
In consideration of the above circumstances, an object of the present invention is to provide a method for producing H-shaped steel capable of suppressing deterioration of a material passing property and deterioration of a shape of a material to be rolled in “supplementary edging rolling” in which light reduction rolling is performed by returning the material to be rolled to an edging caliber after forming a raised part on a web in flat shaping and rolling, to stabilize the supplementary edging rolling.
To achieve the above object, according to the present invention, there is provided a method for producing H-shaped steel, the method including: a rough rolling step; an intermediate rolling step; and a finish rolling step, wherein: the rough rolling step includes: an edging rolling step of rolling and shaping a material to be rolled into a predetermined dog-bone shape; a raised part generating step of performing rolling of a web part by making the material to be rolled after completion of the edging rolling step to be rotated by 90° or 270°, and forming a raised part at a middle of the web part of the material to be rolled; a supplementary edging rolling step of performing light reduction rolling by making the material to be rolled after being rolled in one pass or more in the raised part generating step to be rotated by 90° or 270° again and returning the material to be rolled to a final caliber in the edging rolling step; and a raised part eliminating step of reducing and eliminating the raised part formed in the raised part generating step; in upper and lower caliber rolls which perform the raised part generating step, recessed parts configured to form the raised part at the middle of the web part of the material to be rolled are provided at roll barrel length middle parts of the upper and lower caliber rolls; a roll shape of the upper and lower caliber rolls is designed to make tips of flange parts of the material to be rolled to be out of contact with the upper and lower caliber rolls; two steps of the raised part generating step and the supplementary edging rolling step are continuously performed one time or plural times; and the raised part eliminating step is performed after the raised part generating step and the supplementary edging rolling step are performed.
In the supplementary edging rolling step, the light reduction rolling may be performed so as to make the tips of the flange parts of the material to be rolled fill the final caliber in the edging rolling step.
In the supplementary edging rolling step, the light reduction rolling may be performed so as to make a web height of the material to be rolled to be smaller than a web height of the material to be rolled supplied to a caliber which performs the raised part generating step right before the supplementary edging rolling step.
The supplementary edging rolling step may be performed in one chance or two chances when one set of plural passes in which an edging height in a final pass is set to be constant is set to one chance.
A width of the raised part formed in the raised part generating step may be set to 25% or more and 50% or less of a web part inner size of the material to be rolled.
According to the present invention, it becomes possible to suppress deterioration of a material passing property and deterioration of a shape of a material to be rolled in “supplementary edging rolling” in which light reduction rolling is performed by returning the material to be rolled to an edging caliber after forming a raised part on a web in flat shaping and rolling, to stabilize the supplementary edging rolling.
Hereinafter, an embodiment of the present invention will be explained while referring to the drawings. Note that in the present description and the drawings, components having substantially the same functional configurations are denoted by the same numerals to omit duplicated explanation.
(Outline of Production Line)
As illustrated in
Here, a slab thickness of the slab 11 extracted from the heating furnace 2 is, for example, within a range of 290 mm or more and 310 mm or less. This is the dimension of a slab raw material called a so-called 300 thick slab used when producing a large-size H-shaped steel product.
In the sizing mill 3 and the rough rolling mill 4 illustrated in
Following the edging rolling step, a flat shaping and rolling step is performed as a post-stage step. In the flat shaping and rolling step, the material to be rolled A after being subjected to the edging rolling step is first rotated by 90° or 270°. By this rotation, the flange parts located at the upper and lower ends of the material to be rolled A (slab 11) in the edging rolling step are located on a rolling pitch line. Next, reduction of a web part being a connecting part connecting the flange parts at two positions is performed. By these edging rolling step and flat shaping and rolling step, the H-shaped raw blank 13 illustrated in
Generally, the above pre-stage step and post-stage step are collectively referred to as a rough rolling step. In the method for producing H-shaped steel according to the present embodiment, the edging rolling step being the pre-stage step in the rough rolling step is only required to be performed by a conventionally-known general method. Accordingly, detailed explanation regarding the edging rolling step will be omitted in the present description. Hereinafter, the flat shaping and rolling step being the post-stage step will be described in detail while referring to the drawings.
(Outline of Caliber Configuration)
Here, the upper and lower caliber rolls 85, 86 of the first flat shaping caliber KH1 have shapes formed with recessed parts 85a, 86a of a predetermined length L1 at their roll barrel length middle parts. With such a caliber configuration illustrated in
Note that since the rolling and shaping of partially reducing the web part 82 to form the raised part 82b is implemented in the first flat shaping caliber KH1, this caliber is also referred to as a “web partial rolling caliber”. The width length of the raised part 82b after the formation is the same length as the width length L1 of the recessed parts 85a, 86a. Herein, as illustrated in the enlarged view in
In the second flat shaping caliber KH2, the rolling of bringing the upper and lower caliber rolls 95, 96 into contact with the raised part 82b formed in the web part 82 to reduce (eliminate) the raised part 82b is performed. In accordance with the reduction of the raised part 82b, spread in the web height direction and the metal flow to the flange parts 80 are promoted. Because of the metal flow as above, it becomes possible to implement the rolling and shaping without causing decrease in area of the flange as much as possible. In the present description, the step of reducing (eliminating) the raised part 82b in the second flat shaping caliber KH2 is also described as a “raised part eliminating step”. Further, the second flat shaping caliber KH2 eliminates the raised part 82b formed in the web part 82, so that it is also referred to as a “raised part eliminating caliber”.
Regarding the rolling and shaping in the first flat shaping caliber KH1 and the second flat shaping caliber KH2, their detailed conditions and so on (dimensions, shapes and so on of the calibers) will be described later in more detail based on the finding and so on obtained by the present inventors in the explanation of the present embodiment.
The H-shaped raw blank 13 shaped by being passed through these first flat shaping caliber KH1 and second flat shaping caliber KH2 is subjected to application of reverse rolling in plural passes using the rolling mill train composed of two rolling mills of the intermediate universal rolling mill 5 and the edger rolling mill 9, whereby an intermediate material 14 is shaped. Subsequently, the intermediate material 14 is subjected to finish rolling into a product shape in the finishing universal rolling mill 8, whereby an H-shaped steel product 16 is produced (refer to
In the rough rolling step in the production of H-shaped steel, when performing the edging rolling step and the flat shaping and rolling step, it is known that the reduction in thickness of the web part is performed, and following that, the “supplementary edging rolling” is performed by returning the material to be rolled A to the edging caliber again in order to prevent an overfill from a position of a lateral surface of the flange part of the material to be rolled in the flat shaping caliber, as described above. This “supplementary edging rolling” is a technique conventionally employed for the purpose of adjustment of a shape of an unsteady part of the material to be rolled, suppression of a shape defect such as an overfill, and the like.
(Conventional Supplementary Edging Rolling)
First, conventional supplementary edging rolling will be briefly described with reference to
As illustrated in
In the conventional technique for producing H-shaped steel, the material to be rolled A after being passed through the edging final caliber KE illustrated in
As illustrated in
(Supplementary Edging Rolling According to Present Embodiment)
On the contrary, in the present embodiment, a flat shaping caliber used when performing the supplementary edging rolling employs the “web partial rolling caliber” being the first flat shaping caliber KH1 illustrated in
As illustrated in
It is preferable that the edging rolling of about 40 mm or less, for example, is performed during the supplementary edging rolling, and in this case, a spread amount of the flange width is about 24 mm or less.
Incidentally, when performing the flat shaping and rolling, by setting the web height of the material to be rolled A to be as small as possible with respect to the caliber width length W of the “web partial rolling caliber” being the first flat shaping caliber KH1 (refer to
On the other hand, in order to improve the rolling stability in the flat shaping and rolling, it is demanded to increase the caliber restraining force with respect to the material to be rolled A. Regarding the caliber restraining force, the larger the distance between the caliber roll outer walls of the flat shaping caliber and the material to be rolled A and the larger the amount of widening the web inner size, the lower the inductive property, which destabilizes the rolling. From a point of view of material passing property as above, the edging amount during the supplementary edging rolling is desirably set to be as small as possible.
Based on the above-described reasons, an optimum value of the edging amount during the supplementary edging rolling should be set by considering a balance between occurrence of flaws and the rolling stability. When the flat shaping and rolling is performed after completion of the supplementary edging rolling, it is desirable to design such that side walls (outer walls) of the flat shaping caliber and the web height of the material to be rolled A substantially coincide with each other.
Here, the rolling of the web part 82 is supposed to be plate rolling. Based on a dimensional relationship between a roll diameter of a normal shape steel rolling mill and a material to be rolled of large-size H-shaped steel, a plate width ratio is about 3 to 4, and a plate thickness ratio is about 4 to 5. Besides, since flange parts are provided at both ends in the plate thickness, a spread amount is further increased. As a result of this, a rate of spread in the web height direction of the material to be rolled A due to the web reduction is 4% or more of the web height. Namely, when considering the material to be rolled A with a web height dimension of 1000 mm, for example, as large-size H-shaped steel, a rate of spread of the web height is at least 40 mm. Accordingly, by applying, at the time of supplementary edging rolling, an edging amount of equal to or more than 40 mm being equal to or more than a spread amount of the web height during the flat rolling, as a condition under which the material to be rolled A is not in contact with the caliber roll outer walls of the flat shaping caliber, the material to be rolled is in a state of being in contact with caliber side walls at a roll outlet side in the flat shaping and rolling, and thus from a viewpoint of material passing property and the like, there is no chance that the material passing property is impaired. Specifically, the edging amount during the supplementary edging rolling is preferably set to 40 mm or less.
Further, regarding a flange width spread in accordance with the edging rolling, it is possible to apply a width spread rolling characteristic based on slab edging. Specifically, a flange width spread characteristic based on a conventional slab edging method performed by a caliber which is a so-called box caliber having a projection at a middle part thereof, is applied. In this case, at least approximately 60% or less of a reduction amount is known to be a flange width spread, and thus the flange width spread can be calculated as 40 mm×0.6 (60%)=24 mm.
As illustrated in
The present inventors confirmed, also by experiments, that the material passing property is different according to the filling property in the caliber during the supplementary edging rolling, and there is a problem in the material passing property when the caliber is not filled. Table 1 to be presented below indicates experimental examples showing a relationship between the caliber filling property and the material passing property in the supplementary edging rolling. Table 1 indicates a relationship between the caliber filling property and the material passing property in the conventional method and the method of the present invention under conditions of a case 1 to a case 4. Note that during the supplementary edging rolling, edging rolling with an edging amount of about 40 mm was performed in two passes in all of the cases 1 to 4. For this reason, a value of change in the web height during the supplementary edging rolling indicated in Table 1 is presented as −40 mm in all of the cases 1 to 4.
As indicated in Table 1, when the caliber is filled during the supplementary edging rolling, the material passing property was good. On the contrary, when the caliber is not filled, bending occurred. Further, with reference to the cases 2 to 4, when the same cumulative web reduction amount was employed during the supplementary edging rolling in the conventional method and the method of the present invention, there was a case in which even at the cumulative web reduction amount at which the caliber is not filled in the conventional method, the caliber is filled and thus the material passing property is favorably maintained in the method of the present invention (refer to the cases 2, 3 in Table 1). Note that the edging rolling of about 40 mm was set to be performed during the supplementary edging rolling, so that a value of web height during the supplementary edging rolling indicated in Table 1 is −40 mm in all of the cases 1 to 4.
Next, the present inventors thought that the effect of suppressing the dimensional error and the shape defect differs depending on a schedule design (a reduction amount, a pass schedule, and so on) of the supplementary edging rolling according to the present embodiment. Accordingly, they verified, based on experiments, changes in flange width caused by the supplementary edging rolling in a case of producing H-shaped steel by using a slab having a cross section of 2000 mm×300 mm as a raw material.
Table 2 to be presented below indicates changes in flange width for each pass when performing flat shaping and rolling by the first flat shaping caliber KH1 (namely, the web partial rolling caliber). Cases 1 to 3 in Table 2 differ in the number of times of performing the supplementary edging rolling for each pass of the flat shaping and rolling. When the supplementary edging rolling is performed (namely, the case 2 and the case 3), changes in flange width after performing the supplementary edging rolling are indicated. Further, the description of 15th pass to 23rd pass in Table indicates that edging rolling was performed at a previous stage as first to 14th passes before the flat shaping and rolling, and indicates that the 15th pass and thereafter correspond to the flat shaping and rolling.
During the supplementary edging rolling, the edging rolling of about 40 mm was performed. Concretely, in the case 2, the edging rolling of about 40 mm was performed one time in two passes. In the case 3, the edging rolling of about 20 mm was performed two times continuously in two passes. As indicated in Table 2, a spread amount of the flange width realized by the supplementary edging rolling was about 24 mm in each pass in the case 2, and it was about 44 mm in each pass in the case 3.
Note that the descriptions of “case 2: supplementary edging rolling of one time”, “case 3: supplementary edging rolling of two times” in Table 2 indicate the number of times of the supplementary edging rolling performed in two passes which are set as one set, and the descriptions of the number of times of the supplementary edging rolling in two passes which are set as one set are also described as “one chance”, “two chances”. Practically, the number of times of passes of the supplementary edging rolling in one chance may be one or plural such as two or more, but, the pass schedule is designed by setting that the total edging amount satisfies a certain condition (namely, a condition that an edging height in a final pass is set to be constant).
Further, Table 2 presents, for reference, changes in flange width in each pass when performing the flat shaping and rolling without performing the supplementary edging rolling, as the case 1.
The case 2 in Table 2 indicates flange widths when the supplementary edging rolling under a condition where the spread of the flange width is not restricted is performed by only one chance in each pass indicated in the case 1.
As indicated in the case 2 in Table 2, when performing the supplementary edging rolling in one chance, the flange width after the supplementary edging rolling was greater than an edging caliber width (1010 mm) before the flat shaping and rolling in each of the 15th pass to the 17th pass. For this reason, the filling in caliber is realized in the edging final caliber KE during the supplementary edging rolling. The description of “0” in Table 2 indicates that the filling in caliber is realized and the rolling stability is good.
On the other hand, in the 18th pass and thereafter, the flange width after the supplementary edging rolling was less than the edging caliber width (1010 mm) before the flat shaping and rolling, so that the edging final caliber KE is not filled during the supplementary edging rolling, which may cause the dimensional error and the shape defect. The description of “x” in Table 2 indicates that the caliber is not filled, and thus there is a problem in the rolling stability.
Further, the present inventors also conducted verification regarding a case of performing the supplementary edging rolling in two chances (supplementary edging rolling of two times in Table), as indicated in the case 3 in Table 2. The case 3 indicates flange widths after increasing the number of times of supplementary edging rolling in the 18th pass in which the caliber was not filled in the case 2 and thereafter and performing the supplementary edging rolling under a condition where the spread of the flange width is not restricted in two chances.
When the supplementary edging rolling is performed in two chances, a larger spread of the flange width during the supplementary edging rolling can be expected when compared with the case of one chance, so that the filling in caliber in the edging final caliber KE during the supplementary edging rolling can be realized even in a further subsequent-stage pass. Under the condition of the present verification, the filling in caliber is realized in the edging final caliber KE during the supplementary edging rolling until the 22nd pass, as indicated in Table 2.
It is generally desired that the supplementary edging rolling is stably performed in further subsequent-stage passes in the flat shaping and rolling. This is because as the supplementary edging rolling is performed more in the subsequent-stage passes of the flat shaping and rolling, the dimensional accuracy of the shape of the material to be rolled which is sent for the intermediate rolling and finish rolling being further subsequent-steps improves, resulting in that the rolling stability and the improvement in product dimension accuracy are realized.
Namely, it can be understood that by performing the supplementary edging rolling in two chances, the supplementary edging rolling at a further subsequent stage is realized without causing the dimensional error and the shape defect of the material to be rolled, which realizes efficient rolling.
Further, Table 3 to be presented below indicates, for reference, changes in flange width after the flat shaping and rolling in the conventional method (case 1) and changes in flange width when a flange width spread during the supplementary edging rolling after the supplementary edging rolling is performed after each pass is taken into consideration (case 2). As indicated in Table 3, in the conventional method, the flange width after the supplementary edging rolling is greater than the edging caliber width (1010 mm) before the flat shaping and rolling only in the 15th pass, in which the filling in caliber is realized in the edging final caliber KE during the supplementary edging rolling. On the other hand, in the 16th pass and thereafter, the flange width after the supplementary edging rolling is less than the flange width (1010 mm) before the flat shaping and rolling, so that the edging final caliber KE is not filled during the supplementary edging rolling, which may cause the dimensional error and the shape defect.
As can be understood by comparing Table 2 and Table 3, when the method of the present invention is applied, in a case of performing the supplementary edging rolling in only one chance, it was possible to perform the supplementary edging rolling realizing the filling in caliber until the 17th pass. In a case of performing the supplementary edging rolling in two chances, it was possible to perform the supplementary edging rolling realizing the filling in caliber until the 22nd pass. On the contrary, in the conventional method, it was possible to perform only the supplementary edging rolling realizing the filling in caliber until the 15th pass. Specifically, by applying the method of the present invention, the supplementary edging rolling in further subsequent-stage passes can be performed, and it becomes possible to carry out the rough rolling step with high precision while suppressing the dimensional error and the shape defect such as occurrence of flaws.
(Ratio of Escaping Amount (Raised Part Forming Width) in First Flat Shaping Caliber KH1)
As described above, in the first flat shaping caliber KH1 (refer to
The present inventors found that the width length L1 of the raised part 82b formed in the first flat shaping caliber KH1 (namely, the escaping amount of the web inner size in the rolling and shaping in the first flat shaping caliber KH1, which is also simply referred to as “escaping amount”, hereinafter) is changed to result in a difference in the flange width of the finally obtained H-shaped raw blank. This is attributed to the fact that the flange thickness amount is more easily ensured with an increase in the width length L1 of the raised part 82b, and, on the other hand, the flange width decreases by the drawing action in the longitudinal direction of the material to be rolled A at the time of the subsequent elimination of the raised part.
Accordingly, the present inventors verified the relationship between the escaping amount of the web inner size in the rolling and shaping in the first flat shaping caliber KH1 and the flange width of the finally obtained H-shaped raw blank.
Further, the horizontal axis in the graph of
Escaping percentage [%]=(escaping amount L1/web inner size L2)×100 (1)
The thickness decrease amount at the flange part 80 (a decrease amount of the flange thickness amount) in the first flat shaping caliber KH1 is decreased by increasing the escaping percentage. For this reason, the flange width of the finally obtained H-shaped raw blank tends to increase together with the increase in escaping percentage as illustrated in
Specifically, it is conceivable that in the case of adopting the method of forming the raised part 82b explained in the present embodiment as the production process of large-size H-shaped steel, there is a preferable range of the escaping percentage. Accordingly, the present inventors focused attention on the relationship between the escaping percentage and the increase/decrease of the flange width after the shaping of the H-shaped raw blank, and derived a preferable numerical value range of the escaping percentage.
As illustrated in
In consideration that the rolling and shaping of increasing also the flange width of the H-shaped raw blank is desired in the case of producing a large-size H-shaped steel product having a larger flange width as compared with the conventional one, it can be understood, from the results indicated in
(Operations and Effects)
According to the above-described method for producing the H-shaped steel according to the present embodiment, the flat shaping and rolling performed after the edging rolling, is carried out by using the first flat shaping caliber KH1 which forms the raised part 82b. Consequently, it becomes possible to suppress deterioration of the material passing property and deterioration of the shape of the material to be rolled in the “supplementary edging rolling” in which the light reduction rolling is performed by returning the material to be rolled A to the edging final caliber KE after the flat shaping and rolling, to thereby stabilize the supplementary edging rolling. Further, it becomes possible to roll and shape the H-shaped raw blank 13 having a larger flange width as compared with the conventional one, resulting in that it becomes possible to produce an H-shaped steel product having a larger flange width as compared with the conventional one.
Further, for example, in the case of performing the rolling and shaping of the H-shaped raw blank according to the present embodiment using a raw material, which is called a 300 thick slab, having a thickness of about 300 mm and a width of about 2000 mm, by setting, when using the first flat shaping caliber KH1 being a so-called “web partial rolling caliber” during the flat shaping and rolling, the escaping percentage to fall within a range of 25% to 50% (more preferably about 25%) in the formation of the raised part 82b, it is possible to maximize the flange width of the H-shaped raw blank to be rolled and shaped.
One example of the embodiment of the present invention has been explained above, but, the present invention is not limited to the illustrated embodiment. It should be understood that various changes or modifications are readily apparent to those skilled in the art within the scope of the spirit as set forth in claims, and those should also be covered by the technical scope of the present invention.
For example, although the above embodiment explains that the rolling and shaping is performed on the rectangular cross-section raw material (slab) through the edging rolling as a previous stage of performing the flat shaping and rolling using the first flat shaping caliber KH1, and then the flat shaping and rolling is performed, but, the applicable range of the technique of the present invention is not limited to this. Specifically, the technique of the present invention is also applicable to a case where flat shaping and rolling is performed on a material to be rolled which is not subjected to an edging rolling step such as a beam blank.
The present invention is applicable to a production method for producing H-shaped steel using, for example, a slab having a rectangular cross section or the like as a raw material.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-102423 | May 2017 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2018/019883 | 5/23/2018 | WO | 00 |
