JP3068353B2 - Shape control method for H-section steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the shape of an H-section steel, and more particularly to a method for controlling the shape of an H-beam immediately after being rolled by a universal rolling mill.
The present invention relates to a shape control method for preventing warpage caused by a temperature difference between upper and lower portions of a flange of a section steel.

[0002]

2. Description of the Related Art Rolling of an H-section steel is performed by using a production line such as a coarse universal rolling mill, an edger, and a finishing universal rolling mill. In general, the H-shaped steel 1 exiting the finishing universal rolling mill has a temperature distribution of a cross-sectional shape as shown in FIG. The temperature difference is generated between the upper flange portion 2a and the lower flange portion 2b along the width direction of the flange 2, and the temperature difference causes the warpage as shown in FIG.

Conventionally, in order to reduce such warpage of the H-section steel, a flange cooling method has been used in a production line for the H-section steel, in which cooling water is blown onto a flange of the H-section steel to cool it. . In this flange cooling method, the cooling water density distribution in the flange width direction is often performed symmetrically with respect to the center of the flange width, and in rare cases, the temperature difference between the upper and lower parts of the flange is focused on. Thus, a cooling method that reduces the temperature difference is adopted.

That is, for example, JP-A-52-142613, JP-A-63-248501, and JP-A-1-116033 disclose methods of adjusting the amount of cooling water and reducing the residual stress by injection pattern. And JP 63
Japanese Patent Application Laid-Open No. -186827 discloses a method of providing a reverse warp at a high temperature for cooling, and Japanese Patent Application Laid-Open No. 1-205033 discloses a method of mechanically restraining the warp.

[0005]

However, Japanese Patent Application Laid-Open Nos. 52-142613 and 63-248501, and JP-A Nos.
In the method of controlling the shape of the H-section steel disclosed in No. 6033, etc., all are static control by fixed equipment, and the temperature fluctuates depending on a rolling pitch, a furnace position in a heating furnace, an extraction state, and the like. If the symmetry of the temperature distribution in the flange width direction is lost for these reasons, it is not possible to dynamically respond to the distribution, and there is a problem that warpage occurs in the cooling process.

Further, Japanese Patent Application Laid-Open Nos. 63-1886827 and 1-20
In any of the methods disclosed in No. 5033, there is a concern that the control is unstable, and in particular, the equipment is required for mechanical restraint, so it was attempted to mass-produce multi-size shaped steel. There is a problem that it is not suitable for a factory that does.
In order to solve the above problems, the present applicant has already proposed a method of controlling the shape of an H-beam in Japanese Patent Application No. 3-275532. As shown in FIG. 5, the temperature of the flange of the H-section steel 1 is controlled by a plurality of temperature sensors 4a, 4b, 4c, 4d arranged in the width direction of the upper flange portion 2a and the lower flange portion 2b.
And input those measurement signals to the control unit 7 via the analog multiplexer 5 and the A / D converter 6,
The control unit 7 predicts the residual stress distribution in the upper flange portion 2a and the lower flange portion 2b in the rolling direction of the H-section steel 1 based on the measured temperature, and determines the flange water cooling according to the difference between the predicted values of the residual stress distribution in the upper and lower flange portions. By adjusting the height position of the cooling water injection nozzle 9 by the device 8, it is intended to dynamically respond to the fluctuation of the residual stress distribution and secure the vertical symmetry of the finishing temperature.

More specifically, the above-mentioned invention introduces the concept of a temperature moment and uses it as an index of control. That is, the warpage of the H-section steel is caused by the imbalance of the bending moment based on the residual stresses above and below the flange, and the residual stress is caused by the amount of thermal shrinkage of each part of the flange. Because of the proportional relationship within, the bending moment is replaced by the concept of temperature moment.

If the residual stress generated in the cooling process is proportional to the finishing temperature of each part of the flange, the warpage is obtained by integrating (temperature of each part) × (distance from the center of the flange) in the flange width direction. It is determined by the upper and lower difference of the sum of the temperature moments. In other words, the temperature moment is obtained by multiplying the distance (arm length) from the center in the flange width direction to the temperature measurement point by the measured temperature value, and is integrated vertically and separately from the center to the flange end in the width direction. Ask for.

Now, assume that the flange width of the H-section steel 1 is B,
Let the temperature distribution function of the upper part 2a of the lunge be T _U(x), below the flange
The temperature distribution function of the part 2b is represented by_LIf (x)
Sum M of the temperature moments of the upper and lower parts_U, M_LIs below
Equations (1) and (2) are used. X is from the center of the flange
Is the distance.

[0010]

(Equation 1)

Then, the sum M _U of the temperature moment of the upper flange portion 2a and the sum M of the temperature moment of the lower flange portion 2b are obtained.
Comparing _L, and when M _U> M _L according to the following equation (3),
Also when the M _U ≦ M _L (4) below, respectively to calculate the nozzle moving amount [Delta] H _U according to Formula performing height control of the cooling water jetting nozzles. ΔH _U = L · (M _U −M _L ) (3) ΔH _U = L · (M _L −M _U ) (4) where L is a proportional coefficient.

However, the above-mentioned Japanese Patent Application No. 3-275532 is disclosed.
According to the method of No. 5, according to the investigation by the present inventors, the details will be described later, but the flange temperature distribution before and after reheating after flange cooling is greatly different, and the temperature distribution from the middle stage where reheating is not sufficiently achieved is considered. Because the calculated values are used to control the residual stress above and below the flange that affects the warp shape of the H-section steel, there is a potential problem that accuracy is not sufficient to completely eliminate warpage. is there.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and is intended to predict the flange temperature distribution after reheating when flange water cooling is performed. It is an object of the present invention to provide a method for controlling the shape of an H-section steel which can improve the prediction accuracy of the residual stress distribution of the steel sheet and control the flange residual stress distribution to be optimum by the latter-stage flange water cooling to prevent the occurrence of warpage.

[0014]

According to the present invention, there is provided a shape control method for controlling the warpage of an H-beam by blowing cooling water onto a flange of the H-beam immediately after being rolled by a universal rolling mill. The flange width direction temperature distribution of the section steel is measured at a plurality of positions before and after the water cooling, and based on the measured temperature value, the flange width direction temperature distribution of the H section steel after reheating is predicted. Predicts the residual stress distribution in the upper and lower flanges in the longitudinal direction of rolling based on the above, and adjusts the height position of the cooling water injection nozzle according to the difference between the predicted values of the residual stress in the upper and lower flanges. This is a method for controlling the shape of the H-section steel.

The cooling water injection nozzle may be provided in a plurality of stages in the flange width direction to adjust the flow rate or pressure of the cooling water in each stage.

[0016]

[Operation] The inventor of the present invention disclosed in the aforementioned Japanese Patent Application No. 3-275532 H
An experiment was conducted using the shape control method of the section steel, and the relationship between the upper and lower equivalent temperature difference of the flange and the amount of warpage was investigated. Here, the upper and lower equivalent temperature difference of the flange is the temperature dimension obtained by dividing the upper and lower difference of the sum of the temperature moments, which is a control index, by the value obtained by integrating the distance from the flange center to the temperature measurement point in the flange width direction. Then, assuming that the upper and lower equivalent temperature difference is T _M ,
It can be expressed by the following equation (5). Here, x is a distance from the center of the flange with the upper direction of the flange being positive.

[0017]

(Equation 2)

At this time, temperature sensors are attached to the front and rear of the flanged water cooling device and to the inlet side of the air cooling zone provided at a sufficiently distant position downstream of the flanged water cooling device, respectively. The temperature in the flange width direction was measured by a temperature sensor on the inlet side of the flange water cooling device, and the height of the cooling water injection nozzle of the flange water cooling device was adjusted based on the result. For the next rolled material, the temperature after reheating was measured using a temperature sensor on the air cooling zone entrance side, and the height of the cooling water injection nozzle of the flange water cooling device was adjusted based on the temperature measurement result. FIG. 6 shows the correlation between the flange upper and lower equivalent temperature difference before reheating and the amount of warpage obtained at that time.

FIG. 7 shows the results of measurement of the surface temperature distribution at various positions in the flange width direction of the H-section steel at the same time. The surface temperature distribution before reheating was measured by a temperature sensor on the outlet side of the flanged water cooling device, and the surface temperature distribution after reheating was measured by a temperature sensor on the inlet side of the air cooling zone. From this investigation result, it can be seen that the contribution ratio of the present shape control method is as small as γ ² = 0.22, and thus the variation is large. The reason for this is that the temperature distribution in the flange width direction before and after reheating is different, as can be seen from FIG. 7 above, and therefore, as shown in FIG. This is probably because they are different.

On the other hand, FIG. 9 shows the result of investigating the correlation between the upper and lower equivalent temperature difference after reheating and the amount of warpage measured by the temperature sensor on the inlet side of the air cooling zone. As is clear from this figure,
Contribution rate gamma ² of the shape control method it can be seen that relatively small variations 0.55. The amount of warpage is at a length of 10 m in the rolling longitudinal direction of the H-section steel. From the above results, if the temperature after reheating is predicted from the measurement results of the temperature sensors on the inlet and outlet sides of the flanged water cooling device, the warpage can be accurately controlled.

Therefore, according to the present invention, the residual stress distribution of the flange in the rolling longitudinal direction of the H-section steel when the flange water cooling is performed is increased based on the predicted value of the temperature distribution in the flange width direction after reheating. By accurately predicting and adjusting the height of the cooling water injection nozzle or the flow rate or pressure of the cooling water according to the difference between the predicted values, it is possible to dynamically respond to the fluctuation of the residual stress distribution. As a result, vertical symmetry of the final finishing temperature can be ensured, thereby making it possible to manufacture an H-beam having a shape without warpage.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view showing a main part of an embodiment of the present invention. A plurality of flanged water cooling devices 12a,
A pair of left and right temperature sensors 14a, 14b, 14b for measuring the temperature distribution in the flange width direction of the H-section steel 1 before and after these flange water cooling devices 12a, 12b are connected to each other.
14c is attached, and a temperature sensor 14
d is attached.

Here, the temperature sensors 14a, 14b,
14c and 14d, as shown in FIG. 5 described above, are constituted by arranging a plurality of them in the width direction of the flange 2 of the H-section steel 1, and the temperature measurement signals detected thereby are analog. The data is input to the control unit 7 via the multiplexer 5 and the A / D converter 6 and is subjected to arithmetic processing. The height position of the cooling water injection nozzle 9 is adjusted via the flange water cooling device 8 by a control signal from the control unit 7. Shall be.

Next, a description will be given of an arithmetic processing procedure in the control unit 7 described above. First, the temperature in the width direction of the flange 2 of the H-section steel 1 rolled by the finishing universal rolling mill 10 is measured by the temperature sensor 14a, and the temperature distribution function T _14a (x) is obtained in the control unit 7. Next, the flange portion of the H-section steel 1 is water-cooled by the flange water cooling device 12a, the temperature in the width direction of the flange 2 at the outlet side is measured by the temperature sensor 14b, and the temperature distribution function T _14b (x) Ask for. Then, the temperature distribution function T after the recuperation is
_F (x) is obtained by the following equation (6).

T _F (x) = L ₁ · T _14a (x) + L ₂ · T _14b (x) (6) where L ₁ and L ₂ are proportional coefficients. Where this
As an example of a simple method for predicting the temperature distribution after recuperation by the equation (6), when L ₁ = 1 and L ₂ = −1, that is, the temperature measured from the temperature sensor 14a The correlation between the upper and lower equivalent temperature difference and the amount of warpage due to the temperature drop amount obtained by subtracting
An example is shown in FIG. The contribution ratio γ ² in this figure is
It is 0.21 which is a level that is not exactly different from the one based on the upper and lower equivalent temperature difference before reheating shown in FIG. 6 even with such a simple prediction method. Moreover, obtaining the upper and lower equivalent temperature difference T _MF flange due to temperature distribution function T _F after recuperator described above (x) using the following equation (7).

[0026]

(Equation 3)

Next, a temperature sensor using the upper and lower equivalent temperature difference T _MF of the flange based on the predicted temperature value after recuperation is used.
The moving height ΔH of the cooling jet nozzle of the flange water cooling device 12b at the subsequent stage of 14a, 14b is obtained by the following equation (8).

[0028]

(Equation 4)

Practically, the above equation (8) is changed to
It is preferable to use the following equation (9) in combination with the conventional method of No. 275532, since it becomes possible to obtain an H-section steel with less warpage.

[0030]

(Equation 5)

The moving height ΔH is set to the flange water cooling device.
Output to 12b to control the position of the cooling spray nozzle 9, balance the vertical stress in the longitudinal direction of the flange 2 in the rolling direction, and control the warpage. In the case of the next rolled material, the following equation (1) is used in consideration of the temperature distribution function T _14d (x) after reheating by the temperature sensor 14d on the inlet side of the air cooling zone 13 in the above equation (9).
If the equation (0) is used, the prediction accuracy can be further improved.

[0032]

(Equation 6)

The temperature distribution T of the temperature sensor 14c
_14c (x) and the temperature sensor 14d the temperature distribution T _14d a (x) by feeding each of which can further increase the temperature prediction accuracy itself after heat recuperation. Further, in the above-described embodiment, the height position of one cooling water injection nozzle 9 has been described as being controlled. However, the present invention is not limited to this. Even when the cooling water is provided and the flow rate or pressure of the cooling water in each stage is adjusted, the same operation and effect can be obtained.

Further, the above embodiment has been described with respect to the case of the exit side of the finishing universal rolling mill. However, the present invention can be applied to the case of flange water cooling between the rough universal rolling mill and the finishing universal rolling mill. Needless to say.

[0035]

As described above, according to the method of controlling the shape of the H-section steel according to the present invention, the residual stress distribution of the upper and lower flanges in the rolling direction of the H-section steel is predicted while predicting the temperature distribution after recuperation. Since the height position of the cooling water injection nozzle is adjusted to make it even, the vertical symmetry of the final finishing temperature can be secured with high accuracy, and the warpage of the H-section steel is largely prevented. There is an effect of obtaining.

[Brief description of the drawings]

FIG. 1 is a plan view showing a main part of an embodiment of the present invention.

FIG. 2 is a sectional view of an H-section steel.

FIG. 3 is a schematic diagram showing a temperature distribution in a flange width direction immediately after finish rolling of an H-section steel.

FIG. 4 is a perspective view showing an example of a warped form of an H-shaped steel.

FIG. 5 is an explanatory view of a conventional example of an H-shaped steel shape control device.

FIG. 6 is a characteristic diagram showing a correlation between a vertical equivalent temperature difference and a warpage amount before reheating.

FIG. 7 is a characteristic diagram of a surface temperature distribution at a position in a flange width direction.

FIG. 8 is a characteristic diagram showing a correlation between upper and lower equivalent temperature differences before and after reheating.

FIG. 9 is a characteristic diagram showing a correlation between an upper and lower equivalent temperature difference after reheating and a warpage amount.

FIG. 10 is a characteristic diagram showing a correlation between an upper and lower equivalent temperature difference due to a temperature drop amount and a warpage amount.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 H-section steel 2 Flange 3 Web 5 Analog multiplexer 6 A / D converter 7 Control part 8 Flange water cooling device 9 Cooling water injection nozzle 10 Finishing universal rolling mill 11 Transfer line 12 Flange water cooling device 13 Air cooling zone 14 Temperature sensor

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) B21B 37/74 B21B 1/08 B21B 45/02 C21D 9/00

Claims (2)

(57) [Claims] 1. A shape control method for controlling the warpage of an H-section steel by blowing cooling water onto the flange of the H-section steel immediately after being rolled by a universal rolling mill. Is measured at a plurality of positions before and after water cooling, and the temperature distribution in the flange width direction after reheating of the H-section steel is predicted based on the measured temperature value, and in the rolling longitudinal direction based on the predicted value. Shape control of H-section steel, characterized by predicting the residual stress distribution at the upper and lower flanges and adjusting the height position of the cooling water injection nozzle according to the difference between the predicted values of the residual stress at the upper and lower flanges Method. 2. The method for controlling the shape of an H-section steel according to claim 1, wherein the cooling water injection nozzles are provided in a plurality of stages in the flange width direction to adjust the flow rate or pressure of the cooling water in each stage.