JP5794003B2 - H-shaped steel rolling equipment and rolling method - Google Patents

Description

  The present invention relates to a production facility and a production method for producing H-shaped steel having a thickened portion on a web by rolling.

  2. Description of the Related Art In recent years, the number of buildings has risen, and in order to prevent the collapse and collapse of buildings during disasters such as earthquakes, structural members are required to have excellent plastic deformation ability while ensuring earthquake resistance. For structural members with improved plastic deformation capacity, low YR steel has been developed by adjusting the elements added to the material, and its application results are expanding. However, there is a problem that by reducing the YR, the amount of carbon to be added is increased and the weldability is inferior.

  Here, the H-shaped steel is a structural member having an H-shaped cross section, and is often used for a beam material of a building such as a building or a civil engineering structure. In general, H-shaped steels that are frequently used are low-strength and thin-walled, and have good workability and weldability. However, the size of buildings has been increasing and earthquake resistance and durability have been demanded today. There is an increasing demand for H-section steel that is also excellent in workability. Therefore, by devising the cross-sectional shape, there is a demand for the development of an H-section steel that is excellent in earthquake resistance and durability and at the same time has no poor weldability and workability.

An H-section steel having an irregular cross section is known as a steel material that satisfies such requirements. Patent Document 1 discloses an H-section steel in which the portion connected to the flange of the web portion is thicker than the intermediate portion of the web portion, and the rigidity is improved compared to the conventional H-section steel.
In addition, as a method of manufacturing an H-section steel having a deformed cross section, Patent Document 2 discloses a web including a fillet portion by joining two web ends of a T-section steel and one strip steel strip by butt welding. Discloses a method for producing an H-section steel having a thickened portion. In addition, in this document, two strip steel plates are used as flanges, deformed strip steel plates having thickened portions in the vicinity of both ends of the strip steel plates are used as webs, and each is joined by butt welding, and the plates are joined to the web. A method for producing a modified cross-section H-section steel having a thickened portion is also disclosed.

JP 56-160804 JP 5-195598

Patent Document 1 describes a rule regarding a cross-sectional shape and a comparison of cross-sectional performance with a general H-shaped steel, but does not describe a specific manufacturing method or manufacturing equipment.
Patent Document 2 discloses a method for manufacturing a modified cross-section H-section steel. First, two T-section steels, one strip steel strip, and then the above three Is installed at a predetermined position and then joined by welding. In such a manufacturing method, since the connection part of both flanges and a web is joined by welding, it is necessary to weld twice in a longitudinal direction. Moreover, if it is going to shorten the time of a welding process, it is necessary to introduce a high-density welding heat source, a high frequency resistance welding apparatus, etc., and requires much cost. Similarly, when two strip steel strips and a strip steel strip having thickened both ends are used, much time and cost are required.

The present invention has been made to solve such a problem, and provides an H-section steel rolling facility and a rolling method for manufacturing an H-section steel having a thickened portion at both ends of a web by rolling. It is aimed.
In addition, the H-section steel which has a plate thickness increase part in the both ends of the web targeted by the present invention is mainly intended for beam materials used for buildings of medium and high-rises, for example, having a web height of about 400 to 1000 mm. Is targeted.

(1) A rolling equipment for H-section steel according to the present invention comprises a rough shaping rolling mill, an intermediate rolling mill group having at least one intermediate universal rolling mill, and a finishing universal rolling mill, and a rough shaping rolling mill The web-rolled portion of the upper and lower rolls does not have a convex stepped portion, and at least ½ of the plate thickness difference imparted to the web of the H-shaped steel final product at the width central portion of the upper and lower horizontal rolls of the intermediate universal rolling mill It has the convex step part of the above height, It is characterized by the above-mentioned.

(2) Moreover, in the thing of said (1), in the center part of the width | variety of the top and bottom horizontal roll of the said finishing universal rolling mill, the height of 1/2 of the plate | board thickness difference provided to the web of a H-section steel final product It has the convex-shaped step part of this.

(3) The rolling method of the H-section steel according to the present invention uses a rough rolling process in which the web rolling portion is roughly shaped into a substantially H-shaped flat shape, and an upper and lower horizontal roll having a convex step portion at the center portion of the roll width. An intermediate rolling process in which the central portion of the web is rolled thinner than both ends by the intermediate universal rolling mill, and a web thickness is imparted to the web in the intermediate rolling process using the upper and lower horizontal rolls of the finishing universal rolling mill. And a finish rolling step of rolling so as to achieve a plate thickness difference of the H-shaped steel product with the target plate thickness difference as a target.

(4) Moreover, in the above-mentioned (3), in the finishing rolling step, the upper and lower horizontal rolls of the finishing universal rolling mill with a flat roll outer peripheral shape are used, and only the thickened portion of the web contacts the roll. It is characterized by rolling as described above.

(5) Moreover, in the thing as described in said (3), in a finishing rolling process, the convex level | step difference of the height of 1/2 of the board | plate thickness difference provided to the web of the target H-section steel product in a width center part. The upper and lower horizontal rolls having a portion are used, and rolling is performed such that both the thickened portion and the thinned portion of the web are in contact with the horizontal roll.

(6) Moreover, in the thing in any one of said (3)-(5), when giving plate | board thickness difference to a web by the reciprocating reciprocating rolling by an intermediate | middle universal rolling mill in an intermediate rolling process, it is initial multiple passes. The web reduction ratio of the upper and lower horizontal rolls is made higher than the flange reduction ratio, a thickness difference greater than the final product thickness difference is given to the web surface of the material to be rolled, and the flange reduction ratio is set to the web reduction ratio in the latter period including the final pass. It is characterized by the above.

According to the manufacturing equipment and the manufacturing method of the present invention, it becomes possible to manufacture H-shaped steel having a thickened portion at both ends of the web by rolling, which is extremely effective for improving the production efficiency.
In addition, since the rough shaping rolling mill uses the same roll as a general H-shaped steel manufacturing facility, it is not necessary to change the roll shape in the rough shaping rolling mill, and the cost is not significantly increased. It is possible to roll H-section steel having a thickened portion.

It is explanatory drawing of the rolling equipment which concerns on one embodiment of this invention. It is explanatory drawing of the roll shape used for each rolling mill of the rolling equipment shown in FIG. It is a figure which shows the shape of the horizontal roll of the intermediate | middle universal rolling mill of one embodiment of this invention. It is explanatory drawing of the rolling method of one embodiment of this invention, and is a figure which shows the rolling state in an intermediate | middle universal rolling mill. It is explanatory drawing of the rolling method of one embodiment of this invention, and is a figure which shows the rolling state in a finishing universal rolling mill. It is explanatory drawing of the rolling equipment which concerns on other embodiment of this invention. It is explanatory drawing of the roll shape used for each rolling mill of the rolling equipment shown in FIG. It is a figure which shows the shape of the horizontal roll of the finishing universal rolling mill of other embodiment of this invention. It is explanatory drawing of the rolling method of other embodiment of this invention, and is a figure which shows the rolling state in a finishing universal rolling mill. It is a figure which shows the cross section of the H-section steel made into the manufacture objective in Example 1, 2 of this invention. It is a figure which shows the cross-sectional shape of a to-be-rolled material rolled to the rough rolling process in Example 1, 2 of this invention. It is a figure which shows the cross-sectional shape of the to-be-rolled material rolled to the intermediate rolling process in Example 1 of this invention. It is a figure which shows the cross-sectional shape of a to-be-rolled material rolled to the intermediate rolling process in Example 2 of this invention. It is explanatory drawing of a beam blank. It is a figure which shows the cross section of the H-section steel made into the manufacture objective in Example 3, 4 of this invention. It is a figure which shows the cross-sectional shape of a to-be-rolled material rolled to the rough rolling process in Example 3, 4 of this invention. It is a figure which shows the cross-sectional shape of the to-be-rolled material rolled to the intermediate rolling process in Example 3 of this invention.

[Embodiment 1]
As shown in FIG. 1, a rolling equipment 1 for H-section steel having an increased thickness portion according to the present embodiment includes a rough shaping rolling mill 2, an intermediate universal rolling mill 3, an edger rolling mill 4, and a finish. Universal rolling mills 5 are arranged in order from the upstream side. The roll shape of each rolling mill is shown in FIG. 2. As can be seen from FIG. 2, the roll shapes other than the intermediate universal rolling mill 3 are the same as those for general H-section steel rolling. Only the roll shape of the machine 3 is different from the general one.
That is, the web rolling sections 21a and 21b of the rough shaping rolling mill 2, the upper and lower horizontal rolls 41a and 41b of the edger rolling mill 4, and the upper and lower horizontal rolls 51a and 51b of the finishing universal rolling mill 5 are the upper and lower of the intermediate universal rolling mill 3 described later. The web rolling part which does not have the convex part currently formed in the horizontal rolls 31a and 31b is a flat shape.
On the other hand, the roll shape of the intermediate universal rolling mill 3 has a convex portion (convex stepped portion) at the center of the width of the web rolled portion of the upper and lower horizontal rolls 31a and 31b, as shown in FIG. Yes.

The details of the roll cross-sectional shape of the intermediate universal rolling mill 3 will be described in detail with reference to FIG. The upper horizontal roll 31a and the lower horizontal roll 31b are on both sides of the web-rolled large-diameter portions 32a and 32b and the web-rolled large-diameter portions 32a and 32b at the roll width center portion, and the roll diameter is larger than the web-rolled large-diameter portions 32a and 32b. Web sheet thickening and rolling sections 33a and 33b, and web rolling large diameter sections 32a and 32b and web sheet thickening and rolling sections 33a and 33b are provided with inclined sections 34a and 34b. As described above, the upper horizontal roll 31a and the lower horizontal roll 31b include the web rolling large diameter portions 32a and 32b, the web plate thickness thickening rolling portions 33a and 33b, and the inclined portions 34a and 34b. The portions 32a and 32b protrude and have a convex portion (convex stepped portion).
Note that the web rolling large diameter portions 32a and 32b and the web plate thickness thickening rolling portions 33a and 33b are parallel to each other.
The joints between the inclined portions 34a and 34b, the web rolling large diameter portions 32a and 32b, and the web plate thickness thickening rolling portions 33a and 33b preferably have a smooth shape with an R portion.

The height h of the convex portions of the upper and lower horizontal rolls 31a and 31b is a roll radius difference between the web rolling large-diameter portions 32a and 32b and the web plate thickness thickening rolling portions 33a and 33b, depending on the target product cross-sectional shape. Use rolls with different radii. The width w of the web-rolled large-diameter portions 32a and 32b is a width for rolling the thin web portion during the intermediate rolling process. The width B of the upper and lower horizontal rolls 31a and 31b is the length of the inner method of the H-section steel with a thickened portion that is the target when finishing the intermediate rolling process. Here, the width w of the web-rolled large-diameter portions 32a and 32b may be adjusted to the width of the web cross-sectional thickness portion of the target product cross-sectional shape, but according to the study by the present inventors, the vertical horizontal roll 31a, It has been confirmed that good rolling can be performed when the ratio (w / B) of 31b to width B is in the range of about 0.3 to 0.8.
In the present embodiment, the height h of the convex portion at the central portion of the upper and lower horizontal rolls is set to 1/2 or more of the plate thickness difference between the plate thickness thin portion and the plate thickness increase portion of the target product cross section. The reason why the height h of the convex portion is set in this manner is to form the plate thickness increasing portion only by the intermediate universal rolling mill 3 in the present embodiment.
In addition, about the vertical roll 35, the roll for general H-section steel rolling is used.

The horizontal roll used in the finishing universal rolling mill 5 may not be divided (see FIG. 5A), or has a roll width adjusting function divided into two or more (see FIG. 5B). It may be sufficient if it is possible to contact the sheet thickened portion during rolling and roll.
The horizontal roll of the finishing universal rolling mill 5 shown in FIG. 5 is a flat roll having no protrusions, but even if the protrusions are provided, the height h of the protrusions is the cross section of the product. Since it is substantially the same as a flat roll as long as it is less than half of the difference in sheet thickness between the sheet thickness thin part and the sheet thickness increased part of the web, the horizontal line of the finishing universal rolling mill 5 in this Embodiment 1 is used. This does not exclude the case where the roll is provided with a convex portion having a height less than 1/2 of the difference in plate thickness between the thin plate thickness portion and the thick plate thickness portion of the product cross section.

Next, the rolling method which rolls H-section steel using the rolling equipment 1 shown in the said Embodiment 1 is demonstrated.
As the rolling material, for example, a beam blank as shown in FIG. 14 or a slab having a rectangular cross section is used. This rolled material is shaped and rolled into a general H-shaped steel slab using a roll-shaped rough shaped rolling mill 2 shown in FIG. 2A (rough rolling step).
Next, the intermediate universal rolling mill 3 and the edger rolling mill 4 using the horizontal roll shown in FIG. 2B and FIG. 3 are used to give a sheet thickness difference to the web by repeated reciprocating rolling (see FIG. 4) and the flange. The tip is rolled (intermediate rolling process).

In the case of repeated reciprocating rolling in the intermediate rolling process, when this process is set to the initial stage, the middle stage, and the latter stage, the pass schedule is set so that the initial web reduction ratio is equal to or higher than the flange reduction ratio. This is for imparting a significant difference in sheet thickness to the web in the initial state where the web thickness of the rolled material is thick, and it is preferable that the web reduction ratio is 3% or more higher than the flange reduction ratio.
In the middle period, the relative web reduction ratio with respect to the flange reduction ratio is made lower than that in the initial stage so as to be equal to or higher than the flange reduction ratio, and in the latter period, the flange reduction ratio is made higher than the web reduction ratio. This is to prevent the undulation of the web sheet thickness portion while maintaining the sheet thickness difference imparted to the web at the beginning of rolling.

  Since the web surface is rolled by the upper and lower horizontal rolls with convex portions, the amount of reduction per pass of the plate thickness thin portion and the plate thickness increase portion is equal, but the plate thickness thin portion where the plate thickness before rolling is thin is the same. It is extended in the rolling direction as compared with the thickened portion. However, unless the thickened portion extends in the rolling direction, only the thinned portion cannot extend, and the thinned portion has a wave shape. In order to avoid this, in the middle of rolling, the web reduction ratio is about the same as the flange reduction ratio. The web sheet is thinned, the thickened part, and the flange are rolled so as to have the same extension in the rolling direction.

  In addition, if the flange is excessively squeezed too much, the thickened portion of the web is pulled by the flange in the rolling direction, and the thickness difference applied at the beginning of rolling becomes small. It is preferable to increase the flange reduction rate, and in the latter period, the flange reduction rate is 1% or more higher than the web reduction rate.

  The web rolling reduction mentioned here is {(thickness of web sheet thickness after rolling n (n is an integer equal to or greater than 1))-(thickness of web sheet thickness after n + 1st rolling) Thickness)} / (thickness of web sheet thickness portion after n-pass rolling). The flange rolling reduction is {(n (n: integer of 1 or more) flange thickness after first-pass rolling) − (flange thickness after n + 1-th rolling)} / (nth pass) The thickness of the flange after rolling).

Finally, the finish universal rolling mill 5 performs finish rolling to a target dimension (finish rolling process).
In the finish rolling step, the plate thickness increase portion is rolled so that only the plate thickness increase portions at both ends of the web are in contact with the horizontal roll (see FIG. 5). Fig.5 (a) is a case where a horizontal roll is not divided | segmented, FIG.5 (b) has shown the case where the roll which has the rolling width adjustment function by which the horizontal roll was divided | segmented was used.
In addition, in this rolling method using a flat roll as a horizontal roll of the finishing universal rolling mill 5, when the web height of the intermediate material is reduced during the finish rolling, the thin plate portion of the web may be buckled. . For this reason, this rolling method is preferably applied when the intermediate material is widened by 3 mm or more and finished into a product during finish rolling.

In this embodiment, since the roll of the rough shaping rolling mill 1 and the finishing universal rolling mill 5 can be shared with general H-section steel manufacturing equipment having a constant web thickness, the main rolling equipment 1 is a plate. An H-section steel having a thickened portion can be produced with a small roll purchase investment.
In particular, the roll of the rough shaping rolling mill 1 has a large roll size, and the cost per roll is very high as compared with the rolls of other rolling mills. Therefore, as in the present embodiment, the rough shaping rolling mill 1 By using a roll for general H-section steel rolling, it is possible to roll H-section steel having an increased thickness portion without significantly increasing the cost.

  Further, in the H-shaped steel having the thickened portion at both ends of the web targeted by the present invention, the ratio between the thickness of the thinned portion at the center of the web and the thickness of the thickened portion at both ends of the web is H. Although it is considered that there is a suitable range depending on the use of the shape steel, the above ratio can be easily set to 0.4 or more (less than 1.0) by forming the thickened portion by rolling as in the present embodiment. Can be set and manufactured.

  In the present embodiment, since the differential thickness is applied to the web only by the intermediate universal rolling mill 3, there is a limit to the amount of the differential thickness to be applied, but according to the study by the present inventors, It has been found that a product web thickness of up to 20 mm can be applied.

[Embodiment 2]
Although the rolling equipment 6 which concerns on this Embodiment is shown by FIG. 6, in FIG. 6, the same code | symbol is attached | subjected to the same part as the rolling equipment 1 of Embodiment 1. In FIG.
As shown in FIG. 6, the H-section steel rolling facility 6 having a thickened portion according to the present embodiment includes a rough shaping rolling mill 2, an intermediate universal rolling mill 3, an edger rolling mill 4, and a finish. Universal rolling mills 7 are arranged in order from the upstream side. The roll shape of each rolling mill is shown in FIG. 7. As can be seen from FIG. 7, the roll shapes other than the intermediate universal rolling mill 3 and the finishing universal rolling mill 7 are the same as those for general H-section steel rolling. Only the roll shapes of the intermediate universal rolling mill 3 and the finishing universal rolling mill 7 are different from general ones.
That is, in the first embodiment, convex portions are formed only on the upper and lower horizontal rolls 31a and 31b of the intermediate universal rolling mill 3, but in the second embodiment, as shown in FIG. In addition to the upper and lower horizontal rolls 31 a and 31 b of the machine 3, the web rolling portions of the upper and lower horizontal rolls 71 a and 71 b of the finishing universal rolling mill 7 also have convex portions.

The intermediate rolling mill group is composed of an intermediate universal rolling mill 3 and an edger rolling mill 4, and the shape of the horizontal roll used in the intermediate universal rolling mill 3 is the same as that shown in FIG. It is.
For details of the roll shape of the finishing universal rolling mill, as shown in FIG. 8, the upper horizontal roll 71 a and the lower horizontal roll 71 b are web rolled large diameter portions 72 a and 72 b, web rolled large diameter portions 72 a at the center of the roll width, 72b, web plate thickened portion rolled portions 73a, 73b having a roll diameter smaller than that of the web rolled large diameter portions 72a, 72b, and the web rolled large diameter portions 72a, 72b and the web plate thickened portion rolled portions. Inclined portions 74a and 74b connecting 73a and 73b are provided. Thus, the upper horizontal roll 71a and the lower horizontal roll 71b have the web rolling large diameter portions 72a and 72b, the web plate thickness increased portion rolled portions 73a and 73b, and the inclined portions 74a and 74b, so that the width central portion is provided. It has a shape having a convex portion (convex stepped portion).
In addition, the web rolling large diameter portions 72a and 72b and the web plate thickness increasing portion rolling portions 73a and 73b are parallel to each other.
The joints between the inclined portions 74a and 74b, the web rolling large diameter portions 72a and 72b, and the web plate thickness increased portion rolling portions 73a and 73b preferably have a smooth shape with an R portion.

The height hf of the convex portions of the upper and lower horizontal rolls 71a and 71b is a roll radius difference between the web rolling large-diameter portions 72a and 72b and the web plate thickened portion rolling portions 73a and 73b. The thickness difference between the thick and thin parts and the thickened part is 1/2.
The width wf of the web rolled large diameter portions 72a and 72b is the width of the thin plate portion of the web of the target product cross section. The width Bf of the upper and lower horizontal rolls 71a and 71b is set equal to the target product cross section.
The upper and lower horizontal rolls 71a and 71b of the finishing universal rolling mill may not be divided (see FIG. 9A), or may be a roll having a rolling width adjusting function that can be divided into left and right (see FIG. 9B). It is only necessary that both the thickened portion and the thin portion of the material can be rolled while being in contact with the roll during rolling. In this case, the width wf of the convex portion of the horizontal roll is sent from the intermediate universal rolling mill 3 in this equipment because it can be rolled while constraining the thin plate portion of the web with the convex portion of the horizontal roll during finish rolling. When the web height of the raw material is reduced, the cross section of the product can be finished without buckling the thin plate thickness portion.

  In the case of the divided upper and lower horizontal rolls 71a and 71b shown in FIG. 9B, when the gap between the left and right divided rolls is wide and the length of contact with the thin plate portion is short, the thin plate portion is seated. Since there is a possibility of bending, it is preferable that the length of the upper and lower horizontal rolls 71a and 71b that is in contact with the thin plate thickness portion is 1/2 or more of the thin plate thickness portion.

Next, the rolling method which rolls H-section steel using the rolling equipment 1 shown in Embodiment 2 is demonstrated.
As the rolling material, for example, a beam blank as shown in FIG. 14 or a slab having a rectangular cross section is used. This rolled material is shaped and rolled into a general H-shaped steel piece using a roll-shaped rough shaping rolling mill 2 shown in FIG. 7A (rough rolling step).
Next, the intermediate universal rolling mill 3 and the edger rolling mill 4 using the horizontal rolls shown in FIGS. 7B and 3 impart a plate thickness difference to the web by repeated reciprocating rolling and roll the flange tip. The reduction ratio of the web and flange in each pass is the same as that described in Form 1. (Intermediate rolling process).
Finally, the finish universal rolling mill 7 performs finish rolling to a target dimension (finish rolling process).
In the finish rolling process, as shown in FIG. 9, the thickened portion is flattened so that both the thickened portion of the web at both ends of the web and the thinned portion of the central portion are in contact with the stepped horizontal roll. At the same time, rolling is performed while restraining with a roll so that the thin plate thickness portion does not buckle. For this reason, in the case of finishing rolling, the web can be finished without buckling in either case where the web height of the intermediate material is widened or reduced.
Examples carried out using the rolling equipment 1 and 6 and the rolling method of the present invention are shown below.

Example 1 is a rolling example in the rolling equipment 1 of Embodiment 1 having the roll shape shown in FIG. As shown in FIG. 10, the dimensions of the target H-section steel are a web height of 700 mm, a web plate thickness thin portion of 14 mm, a plate thickness increase portion of 28 mm, a flange width of 250 mm, and a flange thickness of 25 mm.
Using a beam blank with a web height of 560 mm, a flange width of 400 mm, and a web thickness of 120 mm, rough rolling is performed and rolled into a cross section having a web height of 910 mm, a web thickness of 82 mm, a flange width of 275 mm, and a flange thickness of 102 mm as shown in FIG. did. The rough rolling process required 11 passes and was rolled by reciprocating rolling.

Next, rolling in the intermediate rolling process was performed by reciprocating rolling in the same manner as in the rough rolling process, using the upper and lower horizontal rolls 31a and 31b and the vertical roll 35 shown in FIG. At this time, the height h of the convex portion of the horizontal roll was 8 mm, the width w was 350 mm, the number of passes required 21 passes, and rolling was repeated by reciprocating rolling. As a result, a cross-sectional shape having a web height of 698 mm, a flange width of 252 mm, a thin plate thickness of 14.1 mm, a width of 350 mm, and a thick plate thickness increasing portion of 29 mm shown in FIG.
Finally, in the finish rolling process, the horizontal roll of the finish universal rolling mill 5 is rolled using a split roll having a rolling width variable function shown in FIG. As a result of reducing the thickness of only the thickened portion and simultaneously making the flange vertical, the H-section steel having the cross section shown in FIG. 10 could be finished.

Example 2 is a rolling example in the rolling equipment 6 of Embodiment 2 having the roll shape shown in FIG.
The dimensions of the target H-section steel are 700 mm in web height, 14 mm in web thickness portion, 28 mm in thickness increase portion, 250 mm in flange width, and 25 mm in flange thickness (see FIG. 10).
As in Example 1, using a beam blank having a web height of 560 mm, a flange width of 400 mm, and a web thickness of 120 mm, a cross section (see FIG. 11) having a web height of 910 mm, a web thickness of 82 mm, a flange width of 275 mm, and a flange thickness of 102 mm. Finished by 11-pass reciprocating rolling.

  Next, in the intermediate rolling process, an intermediate universal rolling mill and an edger rolling mill 4 are used, as shown in FIG. 13, with a web height of 698 mm, a flange width of 252 mm, a web sheet thickness portion of 14.3 mm, a width of 350 mm, and a sheet thickness increase section. Rolled to a 29.2 mm cross-sectional shape. The number of passes required 21 passes and was formed by reciprocating rolling as in the rough rolling process. The horizontal roll of the intermediate universal rolling mill 3 in this step has a convex part height h of 8 mm and a width w of 350 mm.

Finally, in the finish rolling step, rolling was performed with upper and lower horizontal rolls 71a and 71b with a rolling width variable function having a shape shown in FIG. In addition to the thickened portion of the material web, the thinned portion of the material web was rolled so as to contact the horizontal roll, and rolled to the target cross section in only one pass.
The height hf of the step between the upper and lower horizontal rolls 71a and 71b used in this process was 7 mm, and the width of the convex part was 350 mm including the part where the roll was divided and not in contact with the material. As a result, it was possible to finish the H-section steel having a plate thickened portion on the web of the target cross section.

Example 3 is a rolling example in the rolling equipment 1 of Embodiment 1 having the roll shape shown in FIG. The target dimensions of the H-section steel are as shown in FIG. 15, with a web height of 600 mm, a web plate thickness portion of 12 mm, a plate thickness increase portion of 20 mm, a flange width of 300 mm, and a flange thickness of 22 mm.
Using a beam blank with a web height of 560 mm, a flange width of 400 mm, and a web thickness of 120 mm, rough rolling is performed and rolled into a cross section having a web height of 760 mm, a web thickness of 67 mm, a flange width of 370 mm, and a flange thickness of 96 mm as shown in FIG. did. The rough rolling process required 13 passes and was rolled by reciprocating rolling.

  Next, rolling in the intermediate rolling process was performed by reciprocating rolling in the same manner as in the rough rolling process, using the upper and lower horizontal rolls 31a and 31b and the vertical roll 35 shown in FIG. At this time, the height h of the convex portion of the horizontal roll was 4.5 mm, the width w was 300 mm, the number of passes required 11 passes, and rolling was repeated by reciprocating rolling. As a result, the cross section of the web height 598 mm, flange width 302 mm, plate thickness thin portion 14.1 mm, web plate thickness thin portion width 300 mm, and plate thickness increase portion 22 mm shown in FIG. At this time, the reduction ratio of the web thin portion and the flange of each pass is as shown in Table 1 below.

  Finally, in the finish rolling process, the horizontal roll of the finish universal rolling mill 5 is rolled using a split roll having a rolling width variable function shown in FIG. As a result of reducing the thickness of the thickened portion and simultaneously making the flange vertical, the H-section steel having the cross section shown in FIG. 15 could be finished.

[Comparative Example 1]
Comparative Example 1 is an example in which the same cross section as the H-section steel produced in Example 3 was rolled according to the pass schedule shown in Table 2 below.

  The equipment in which the rolling was performed, the target final production cross section, the intermediate rolling process end section, and the rough rolling process end section were the same as in Example 3. As shown in Table 2, when the web reduction ratio in the intermediate rolling process is equal to or greater than the flange reduction ratio in all passes, the thin plate portion of the web swells in the ninth pass. It was not possible to roll to the target intermediate rolling process end section, and to the final product section.

[Comparative Example 2]
Comparative Example 2 is an example in which the same cross section as the H-section steel produced in Example 3 and Comparative Example 1 was rolled according to the pass schedule shown in Table 3 below.

  The equipment used for rolling, the target final production cross section, and the cross section at the end of the intermediate rolling process are the same as described above, but the cross sectional shape at the end of the rough rolling is as follows: web height 760 mm, web thickness 52 mm, flange width 370 mm, flange thickness The cross section was 96 mm. As shown in Table 3, the rolling reduction ratio of the web and flange in the intermediate rolling process is set to the initial web rolling reduction ratio below the flange rolling reduction ratio and rolled to the final 11th pass. The plate thickness difference was 7.0 mm, and the web thickness difference of 8.0 mm of the target cross section could not be provided.

DESCRIPTION OF SYMBOLS 1 Rolling equipment 2 Rough shaping rolling mill 21a, 21b Web rolling part of rough shaping rolling mill 3 Intermediate universal rolling mill 31a, 31b Upper and lower horizontal roll of intermediate universal rolling mill 32a, 32b Large diameter part of web rolling 33a, 33b Thickening of web plate Thick part rolling part 34a, 34b Inclined part 35 Vertical roll 4 Edger rolling mill 41a, 41b Vertical horizontal roll of edger rolling mill 5 Finishing universal rolling mill 51a, 51b Vertical rolling of finishing universal rolling mill 6 Rolling equipment 7 Finishing universal rolling mill 71a Upper horizontal roll 71b Lower horizontal roll 72a, 72b Web rolling large diameter part 73a, 73b Web plate thickness thickening part Rolling part 74a, 74b Inclined part

Claims (3)

It comprises a rough shaping rolling mill, an intermediate rolling mill group having at least one intermediate universal rolling mill, and a finishing universal rolling mill. have not, have at least an intermediate universal rolling mill of the upper and lower horizontal half or more of height convex stepped portion of the width center portion of the plate thickness difference to be applied to the web of the H-shaped steel end product roll, the finish the width center portion of the upper and lower horizontal rolls of the universal mill, the H-beam, characterized in that have a convex stepped portion of 1/2 of the height of the plate thickness difference to be applied to the web of the H-shaped steel end product Rolling equipment. Rolling the central part of the web thinner than both ends by an intermediate universal rolling mill using a rough rolling process in which the web rolling part is roughly shaped into a flat, substantially H-shaped shape, and an upper and lower horizontal roll having a convex step part at the central part of the roll width. The sheet thickness of the H-section steel product that targets the sheet thickness difference imparted to the web in the intermediate rolling process using the upper and lower horizontal rolls of the finishing universal rolling mill. With a finish rolling process that rolls to make a difference ,
In the finish rolling process, using a vertical horizontal roll having a convex stepped portion having a height that is ½ of the thickness difference to be imparted to the web of the target H-shaped steel product in the center of the width, the thickness of the web is increased. A rolling method for H-section steel, characterized in that rolling is performed such that both the portion and the sheet thickness portion are in contact with a horizontal roll .   In the intermediate rolling process, when a sheet thickness difference is imparted to the web by repeated reciprocating rolling with an intermediate universal rolling mill, the web reduction rate by the upper and lower horizontal rolls of the initial multiple passes is made higher than the flange reduction rate, and the web surface of the material to be rolled 3. The method for rolling H-section steel according to claim 2, wherein a thickness difference equal to or greater than the final product thickness difference is imparted to the latter, and the flange reduction rate is set to be equal to or greater than the web reduction rate in the latter period including the final pass.