JPH0671612B2 - Manufacturing method of steel plate with partial protrusion in width direction - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a steel sheet with a partial protrusion in the width direction which is used as a structural member, a floor board, an exterior material, or the like.

[Conventional technology]

Regarding the steel plate with protrusions used for the structural material of steel structures,
For example, the device described in Japanese Utility Model Laid-Open No. 63-67119 is known, and in addition to this, rolled steel plates provided with projections of various shapes such as stripes, diamonds, lattices, and ribs have been developed.

The use of such a steel plate with protrusions tends to expand, and for example, it is used as a structure in which a steel plate and concrete are integrated, a structure requiring strength for civil engineering, a floor plate, an exterior material, or the like. In addition, with the expansion of applications, the types of steel plates with protrusions have further diversified, and what has recently been particularly required is a steel plate with partial protrusions in which protrusions 2 and flat portions 3 are alternately formed as shown in FIG. 1 (Japanese Patent Application No. 63-290458)
No.).

Among the steel plates with partial projections, the one that has been often used conventionally is a so-called flat projection steel plate with flat surfaces only at both ends in the width direction and a projection in the center. This is a flat surface at both ends for edge trimming and welding,
To control the shape of the entire plate during rolling, it was sufficient to consider only the difference between the central part and both ends.

[Problems to be Solved by the Invention]

However, as shown in FIG. 11, the steel plate with partial projections of the present invention has flat portions 3 at both ends in the plate width direction, and the projections 2 and the flat portions 3 are alternately formed. Shape control is even more difficult. Establishing shape control when rolling such a steel plate with partial protrusions and stabilizing the quality is a prerequisite for expanding the applications of the steel plate with flat protrusions.

Conventionally, when manufacturing a steel sheet having a protrusion and a flat portion in the width direction, the groove depth of the roll is adjusted in order to simply make the average thickness of the protrusion and the plate thickness of the flat portion substantially equal. Therefore,
Regarding the shape of the rolling roll, a smooth arc-shaped crown was provided in the cylinder length direction to stabilize the shape, as in general rolling.

However, this method is not applicable to the production of various steel plates with partial protrusions, and the shape changes depending on the rolling conditions (changes in material temperature, inlet plate thickness, etc.), and a partially stable steel plate with a stable shape can be obtained. Cannot be manufactured. That is, the conventional method could not sufficiently secure the flatness especially at the edge portion.

The present invention is intended to solve the above-mentioned problems in the prior art, and in particular to enable the production of a steel plate with a partial projection having a stable shape with a small steepness at the edge portion.

[Means for Solving the Problems]

The present invention conducts various rolling tests, considers k (t / T) as the shape stability condition of the rolled steel sheet from the sheet thickness T before rolling, the sheet thickness t after rolling, and the transverse flow index k. By making / T) constant, it was discovered that a steel plate with partial projections having a stable shape with a small steepness particularly at the edge portion can be obtained, and it was made based on that finding.

The steepness is a value obtained by dividing the wave height δ (mm) of the plate wave due to the flatness defect by the wave pitch 1 (mm) when the rolled steel plate 10 has a flatness defect as shown in FIG. Yes, the smaller this value, the better the flatness.

In the method for manufacturing a steel sheet with partial projections in the width direction of the present invention, when rolling a steel sheet with partial projections having alternating projecting portions and flat portions in the sheet width direction, first, for each sheet width direction predetermined section, Where L: length before rolling in a predetermined section in rolling direction l: length after rolling in a predetermined section in rolling direction T: strip thickness before rolling t: strip thickness after rolling k: strip width after rolling in a predetermined section in strip width direction The transverse flow index, which is given as the ratio of the sheet width before rolling to the sheet width before rolling, is calculated based on the rolling force function and past actual operation data.
The control output value for the shape control means of the rolling mill is obtained so that the value of the above equation (1) becomes substantially equal in each predetermined section.

Here, the transverse flow index k is defined as a ratio of the width W before rolling and the width w after rolling in a predetermined section in the plate width direction of the rolled steel plate, Given in.

On the other hand, as shown in FIGS. 2 (a) and 2 (b), from the relationship between the length L in the rolling direction of the predetermined section before rolling and the length l of the section after rolling, TWL = twl ... (3), the condition of the equation (1) is given by the equations (2) and (3).

That is, equation (1) is the elongation ratio L / l in the longitudinal direction before and after rolling.
It means that the condition of shape stability is to keep the width constant in the width direction.

As the shape control means of the rolling mill, there is a bender of the rolling roll position, a roll crown adjustment by a variable crown roll as a backup roll, a roll shift of the work roll, a width direction control of the rolling lubricant, and the like. Shape control can be performed by a combination or the like.

However, in the conventional method of providing a smooth arc-shaped entire roll crown in the cylinder length direction and simply adjusting the groove depth of the roll, for example, as shown by the solid line in FIG. k (t / T) fluctuates greatly, and as a result, the steepness (the steepness is shown as a percentage in FIG. 8) also increases at the edge portion, as shown in FIG. In many cases, it is not possible to sufficiently suppress the steepness of this portion.

Therefore, according to the present invention, when rolling such a steel plate with partial protrusions, in addition to the general arc-shaped whole roll crown which is smooth in the cylinder length direction, in the plate width direction specific section where the fluctuation of k (t / T) is large. It was decided to roll by providing a projecting partial crown for stabilizing the rolling shape.

That is, k (t / T) is made substantially equal in this specific section by using a rolling roll provided with a projecting partial crown in a specific section that is difficult to control sufficiently by the shape control means of the rolling mill. Then, rolling is performed so that the steepness in this specific section is low (close to 0 as much as possible).

The position of this partial crown is, for example, a section of about 100 to 150 mm in a specific section (usually near both ends of the rolled steel sheet) where the deviation of the value of k (t / T) becomes large, and the height of the protrusion is, for example, It is a very small value such as 0.12 mm. FIG. 9 shows the relation between the whole crown and the partial crown in this rolling roll in an exaggerated manner in the drawing, and the distinction between the flat portion and the protruding portion and the groove processing for forming the protruding portion are omitted. .

As described above, when the difference in the value of the formula (1) in each predetermined section in the plate width direction is larger than the set value and sufficient adjustment cannot be performed by the shape control means, a rolling roll provided with a partial crown is provided. However, by preparing several types of rolling rolls with partial crowns in advance according to the deviation of the k (t / T) value, etc., an appropriate rolling roll shape can be selected and rolled. It can be performed.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1 (a) and 1 (b) schematically show a plate cross section before rolling and a plate cross section of a product (after rolling) in which flat portions and protrusions are alternately formed, and the shape stability described above is shown. condition is, Becomes

Next, consider k (t / T) in the plate width direction.

The lateral flow index k greatly changes in the plate width direction, particularly at the edge portion due to the influence of the plate crown. Of course, it also changes depending on conditions such as the plate thickness T before rolling and the plate thickness t after rolling.

FIG. 3 shows the distribution of the transverse flow index k in the sheet width direction under the conditions of T = 4.5 mm, t = 3.2 mm, material C ^% = 0.05, and rolling temperature 980 ° C.

This cross flow index k can be obtained from past actual operation data and given in the form of an empirical formula. For example, k = ax ⁴ +1 where x: length ratio from center to edge in the plate width direction (x = 0 at center, x = 1.0 at edge) a: expressed as a constant, and in the example of FIG. 3, a = It becomes 1.1.

On the other hand, the plate pressure ratio t / T changes depending on the load conditions. Fig. 4 is the same T = 4.5mm, t = 3.2mm, material C ^% = 0.05, rolling temperature 980 ℃
Under the condition, the distribution of t / T in the plate width direction according to the load condition is shown assuming that the roll groove depth is uniform, and can be obtained as follows.

That is, the rolling load P per unit width is based on the known rolling theory, However, k _fm : Deformation resistance R: Roll radius Δh: Rolling down amount (= T−t) Q _p : Rolling down force function can be calculated, and the plate width B is used for this (T−t) Can be calculated to obtain t / T.

FIG. 10 shows a control procedure of the shape control means in the manufacturing method of the present invention.

First, as described above, the transverse flow index k and the plate thickness ratio t / T as theoretical values are obtained for each predetermined section in the plate width direction, and k (t / T) is calculated (i = 1, 2, ..., n).

When the value of k (t / T) in each section is compared, and the difference is within the set value, it is judged as the controllable range by the shape control means, and the control output is given to the roll bender or the variable crown roll. I do.

5 and 6 conceptually show the relationship between the bender pressure, the pressure of the variable crown roll and the steepness, respectively. Obtain these relationships under various conditions based on past operation data, and obtain the bender pressure and the pressure of the variable crown roll necessary to eliminate the steepness calculated, and use them for control. You can The relationship between the roll crown and the steepness, and the relationship between the steepness when the shape control is performed by work roll shift or the like are similarly obtained based on the actual operation data, and these are stored in the control device.

The values of k (t / T) in each section are compared, and if the difference is not within the set value, no control command is issued, and usually k (t / T).
The rolling roll shape with an appropriate partial crown is selected in the section corresponding to the vicinity of both ends of the rolled steel sheet where the fluctuation of the value of (T) becomes large, and the value of k (t / T) is corrected by the partial crown to carry out rolling. To do.

The criterion for determining whether or not the control by the shape control means is possible depends on, for example, whether or not the steepness is within 0.5% over the entire width by the shape control means of the rolling mill.

FIGS. 7 to 9 and 13 show an example of a case where roll processing with a partial crown is performed based on the method of the present invention.

The rolling conditions are T = 4.5 mm, t = 3.2 mm, material C ^% = 0.05, and rolling temperature is 980 ° C. The roll crown shape is based on the conventional concept of aligning the average sheet thickness (roll roll shape (whole roll). In order to keep k (t / T) almost constant in the width direction, the height h = 12 as shown in FIG. 9 is set in a specific section corresponding to the edge of the rolled steel plate.
A 0 μ partial crown 4 was provided. As a result of conducting a rolling experiment with the roll and then rewinding the rolled steel sheet in the cold and confirming the shape, it was confirmed that a good shape was obtained. The rolling load at this time is 1500 tons, and as shown in FIG. 7, in the conventional method, there is a change in k (t / T) at the edge portion,
While the steepness increases as shown in FIG. 8, in the method of the present invention, by providing the partial crown 4 and controlling the shape, k (t / T) becomes substantially constant in the plate width direction, The steepness also decreased in the whole widthwise section.

FIG. 13 corresponds to FIG. 9, and the roll shapes of the upper roll 11 and the lower roll 12 and the rolled steel plate 10 at the time of manufacturing the steel plate 10 with partial protrusions.
It shows the relationship with the plate shape. This example is an example of a steel plate with partial protrusions that have protrusions only on the surface (upper surface), and the projections have less projections and depressions than they actually are (in Fig. 9, groove processing of the rolling roll corresponding to the protrusions is omitted. ), And similarly to the case of FIG. 9, the size of the partial crown 4 and the curvature of the central axis 13 during the rolling of the upper roll 11 are exaggerated.

〔The invention's effect〕

According to the method of the present invention, k (t / T) is substantially constant over the entire width in the strip width direction by providing the rolling roll with a partial crown in addition to the smooth arc-shaped entire roll crown in the cylinder length direction. Can be controlled to
It is possible to obtain a steel plate with a partial projection having a small steepness and excellent flatness.

That is, even when it is difficult to suppress the steepness in the vicinity of both ends in the plate width direction of the rolled steel plate only by the shape control means of the rolling mill, a partial crown is provided, and k (t / T) is plated based on the partial crown. By correcting and controlling so that it becomes almost constant in the width direction, the shape stability condition is satisfied and the flatness can be greatly improved.

[Brief description of drawings]

1 (a) and 1 (b) are sectional views of a rolled steel sheet for explaining the shape stabilizing conditions in the present invention, and FIGS. 2 (a) and 2 (b).
(B) is a perspective view for explaining the transverse flow index, FIG. 3 is a distribution diagram of the transverse flow index in the plate width direction, FIG. 4 is a distribution diagram in the plate width direction in relation to the load of t / T, and FIG. FIGS. 6 and 6 are graphs showing the relationship between the bender pressure and the pressure of the variable crown roll and the steepness in the shape control, and FIGS. 7 and 8 are k () in the comparative experiment of the method of the present invention and the conventional method, respectively. t / T) and a graph showing the distribution of steepness in the plate width direction, FIG. 9 is a diagram showing an example of application of a partial crown in the embodiment of the present invention, FIG. 10 is a flowchart of the manufacturing method of the present invention, and FIG. The figure is a perspective view showing an example of a steel plate with partial protrusions, FIG. 12 is an explanatory view of steepness, and FIG. 13 is a schematic sectional view showing a relationship between a roll shape and a plate shape in an embodiment of the present invention. . 1 ... Steel plate with partial projection, 2 ... Projection part, 3 ... Flat part,
4 …… Partial crown, 10 …… Rolled steel plate, 11 …… Upper roll, 12 …… Lower roll, 13
...... Roll center axis

Claims (2)

[Claims] 1. When rolling a steel plate with partial protrusions having alternating projecting portions and flat portions in the sheet width direction, at every predetermined section in the sheet width direction, Where L: length before rolling in a predetermined section in rolling direction l: length after rolling in a predetermined section in rolling direction T: strip thickness before rolling t: strip thickness after rolling k: strip width after rolling in a predetermined section in strip width direction And the cross flow index given as the ratio of the strip width before rolling, and the control output value to the shape control means of the rolling mill is calculated so that the value of the above formula (1) becomes substantially the same in each of the predetermined sections, and in the cylinder length direction. In addition to a smooth arc-shaped whole roll crown, by using a rolling roll provided with a projection-shaped partial crown for a specific section difficult enough shape control by the shape control means of the rolling mill, in the specific section A method for manufacturing a steel sheet with partial projections in the width direction, which comprises rolling after correcting the deviation of the value of the formula (1). 2. The method for manufacturing a steel plate with partial projections in the width direction according to claim 1, wherein the partial crown is provided in a specific section near both ends in the width direction of the plate where the variation of the formula (1) becomes large.