JPH06102201B2 - H-section steel hot rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) In the field of H-section steel, the number of small lots and multiple sizes is gradually progressing, and the number of cases where a small amount of a specific product cross section is ordered is increasing.

The present invention relates to a method for rolling H-section steel that can easily cope with such a situation.

(Prior Art) In order to optimize the cross-sectional performance depending on the purpose of use, there are H-shaped steels having several different product cross-sections with different web and flange thicknesses even within the series of the same nominal size.

Normally, only the necessary amount is rolled according to the order from the user, but in such rolling, it was very difficult to prevent the increase in productivity and manufacturing cost.

The reason is that in the past, when ordering a small amount of a specific product cross section,
Since one material / one product cross section is the minimum unit of rolling, we used rolling materials that weigh as close as possible to the product weight. By the way, if the weight of the rolled material becomes smaller, the rate of occurrence of so-called crops (unsteady parts) that cannot be commercialized at the leading and trailing edges of the material will increase and the yield will decrease. In addition, due to equipment and process restrictions, there is a limit to the use of the minimum weight rolling material, and even if such a material can be used, it is inevitable that a product longer than the ordered length will be rolled. However, a decrease in productivity cannot be avoided. Furthermore, the length and quantity of the products are different, which causes a problem that the number of man-hours required for transportation is significantly increased.

(Problems to be Solved by the Invention) It is an object of the present invention to propose a rolling method of H-section steel capable of solving the above-mentioned conventional problems.

(Means for Solving the Problem) The present invention is to perform hot rolling of H-section steels having at least two types of product cross-sections having different thicknesses from one rolling material, in the final pass of rough rolling by a rough universal mill. ,
After stopping the rolling of the rolling material in the middle of the rolling of the pass, bite back, and perform one or more rolling to form at least two types of cross sections having different thicknesses in the longitudinal direction of the rolling material, Next, a rolling method of H-section steel is characterized in that finish rolling is sequentially performed to a thickest region and a thinner region while appropriately adjusting the roll interval of the finishing universal mill. It is recommended to use a roll with a variable width horizontal roll.

Here, to bite back the rolled material means to pull back the rolled material in a direction opposite to the traveling direction (rolling direction) of the rolled material.

(Operation) FIG. 1 shows an outline of rolling equipment suitable for carrying out the present invention. Reference numeral 1 in the drawing is a breakdown mill that rolls a rolling material such as billet or other small steel piece to a predetermined cross-sectional shape, 2 is a rough universal mill that performs rolling between the breakdown mill 1 and the finishing universal mill, An edger mill 3 reduces the thickness of the rolled material having a web and a flange to a predetermined thickness under a rolling schedule of a plurality of passes by reciprocating between the rough universal mill 2 and the edger mill 3. 4 is a finishing universal mill for finishing the rolled material that has passed through the rough universal mill 2 and the edger mill 3.

In order to roll at least two kinds of H-section steels having different product cross-sections from one small steel piece, first, a web which has passed through the breakdown mill 1 is used based on the largest shaped steel product to be rolled. And the rolled material h having the flange is rolled by the rough universal mill 2 and the edger mill 3 until the desired cross section is obtained as shown in FIG. 2 (a).

Then, in the final pass of the rolling process by the rough universal mill 2 and the edger mill 3, the rolling is stopped and bited back in the middle of rolling, and at least two types of cross sections having different thicknesses in the longitudinal direction of the rolled material are obtained. Rolling is performed once or more. That is, as shown in FIG. 2 (b), the roll interval of the mill 2 is narrowed so that a section different from the previous section (section formed by rolling in FIG. 2 (a)) is formed. Roll, but when rolling to P ₂ , adjust the roll of the edger mill with P ₁ and distance between U ₁ -E ₁ = P ₂ -P
₁ (during distance. Distance measuring method based on the rotational speed of the rolls is employed) to resume rolling so as not to pressure the flange width opening a roll of Ejjamiru 3 at a distance as a rolling material in P ₂ When it reaches, as shown in FIG. 2 (c), the rolling roll is reversed and bite back is performed.

The region 1 in which the bite-back rolling is performed is a portion that becomes another shaped steel product different from the region L that is the largest size product, and the rolling length P ₂ of this region is the product size required in advance. Determined by

This rolling may be repeated several times to obtain shaped steels of different sizes. Then, in the finishing universal mill 4 following this rolling, while appropriately adjusting the roll interval of the mill 4, the finishing rolling is performed from the region having the largest cross section to the region of the smaller cross section in order to also raise the flange.

Next, as shown in FIGS. 3A and 3B, the finishing universal mill 4
In this case, rolling from a thicker area is shown.In such a case, the thicker area will be empty at this point, but in the reverse pass on the return, the roll gap is adjusted and rolled by a predetermined distance. do it.

When the rolling load is large, the bite-back rolling can be performed twice or more.

In the present invention, since the rolling is performed according to the above-mentioned procedure, by increasing the number of bite-back times as necessary, it is possible to roll several kinds of products having different cross-sectional dimensions, particularly within a series having the same nominal dimension. Therefore, it is not necessary to use a material having a high crop generation rate and a small weight, and it is possible to prevent the productivity from decreasing as much as possible.

Figure 4 shows the rolled material on the exit side of the finishing mill.
This rolled material is a non-defective part of product A and product B and the crop c ₁ ,
It is possible to obtain an as-roll product including c ₂ and the section c _{3 having a} different cross section.

In order to reduce the rolling loss in such cross-section rolling, it is necessary to accurately measure the length during biting rolling in the rolling process by the rough universal mill 2, for example, at a constant interval from the center of the mill. A general measuring instrument that is arranged and can detect the presence or absence of rolled material can be adopted.

Further, when a variable width roll 4a as shown in FIG. 5 is used as a horizontal roll for reducing the thickness from the inside of the rolled material in the finishing universal mill 4, the roll width of the horizontal roll is kept constant while keeping the roll interval of the vertical roll 4b constant. By changing W, the flange thickness is constant and the web height is different.
It is also possible to roll a section steel, or conversely, to roll an H section steel having a constant web height, although the flange thickness is different.

As a specific rolling procedure in this case, first, the roll width is set according to the product size in which the thickness of each part is the thickest, and rolling is performed over the entire length of the rolled material. At this time, the thin portion remains unrolled, and therefore, the roll width may be set to match the area and rolled back by biting.

In carrying out the present invention, a rolling schedule for balancing the web and the flange is required, but the most preferable rolling schedule is a rolling schedule for a product having a relatively thin thickness and rolling to a thick product. It is a case. Here, the cross section of a general H-section steel is H12 ″ × 12 ″ in inch size as an example, as shown in FIG. 6, there are two thickness ratios of the flange and the web. The reduction balance of can be kept appropriate.

(Example) In the H300 x 300 (web height x flange width, unit mm) series, the most common cross-sectional size is H300 x 300 x 10
X 15 (web height x flange width x web thickness x flange thickness, unit mm).

Here, there are H304 × 301 × 11 × 17 in this series, and in this embodiment, first, the H-shaped steel having a size of H304 × 301 × 11 × 17 is preferentially sampled for the order length, and the remaining amount is used. Size H300 × 300 × 10 × 15 with a highly applicable cross section
It was decided to roll the H-section steel. The material (maximum weight limit) used for this rolling was based on a small H-shaped steel. In bite-back rolling in rough rolling and finish rolling, the rolling material is usually a little thin, so the roll intervals were set in consideration of the respective amounts.

In finish rolling, the roll interval is set where the thickness of the rolled material is thickest, and rolling is performed over the entire length first, and then the roll interval is adjusted to the area with the smaller size and the specified length is applied from the rear end side of the rolled material. The bite back rolling was performed.

The pass schedule for rough rolling is shown in Table-1, and the pass schedule for finish rolling is shown in Table-2.

By applying reduction under the pass schedule according to the table above, H-shaped steels of different sizes can be obtained from one material without causing shape deterioration, etc., and the crop cut-off rate at this time is 1.0%, It was confirmed by rolling that two materials were used and the crop cut-off rate under the same conditions in two-section rolling was 1.5%, which was significantly improved.

(Effects of the Invention) According to the present invention, even if an H-section steel with a low utilization rate needs to be manufactured according to an order from a user, it can be rolled together with an H-section steel with a high utilization rate. Does not significantly increase, and the crop cut-off rate can be reduced as much as possible. Further, since it is not necessary to use a material having a particularly short length, productivity can be improved, and material stock amount and material management man-hours can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a layout of rolling equipment suitable for carrying out the present invention, FIGS. 2 (a) (b) (c), and FIG. 3 (a) (b) are in accordance with the present invention. FIG. 4 is a plan view of an H-section steel obtained by rolling according to the present invention, FIGS. 5 (a) and 5 (b) are views showing another example of the present invention, and FIG. 6 is a web. It is a graph which shows the relationship between thickness and flange thickness. 1 …… Breakdown mill 2 …… Coarse universal mill 3 …… Edger mill 4 …… Finishing universal mill W …… Roll width

Claims (2)

[Claims] 1. When continuously hot rolling an H-section steel having at least two types of product cross sections having different thicknesses from one rolling material, in a final pass of rough rolling by a coarse universal mill, After stopping the rolling of the rolled material at once, it is bitten back to perform at least one rolling to form at least two types of cross sections having different thicknesses in the longitudinal direction of the rolled material, and then the roll interval of the finishing universal mill. A method for rolling H-section steel, which comprises sequentially finishing rolling into a thickest region and a thinner region while appropriately adjusting the above. 2. The rolling method according to claim 1, wherein a finish universal mill having a horizontal roll having a variable roll width is used for finish rolling.