JPS5920401B2 - Steel plate width control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the width when obtaining steel strip by hot rolling.

When steel strip is obtained by hot rolling, its width varies depending on various factors.

If this amount of width change is large, trimming (margin) will be large when finishing the steel strip with a constant width after hot rolling, for example with a side trimmer, resulting in a decrease in yield.

When hot rolling a slab to obtain a steel strip, there are various factors that cause width variations, but the most significant factor is temperature variation.

Figures 1 and 2 show the relationship between the material (rolled material) temperature (temperature at the center point in the width direction) during the rough rolling stage of hot rolling of steel strip and the width of the material after aging in a hard roll stand. shows.

In Figure 1A, Tmin is the minimum temperature, Tma
x indicates the maximum temperature.

Ti represents the temperature at a distance ti in the length direction from the head of the material, and ΔTi is the difference between Ti and Tm1n.

Figure 1 shows the material width situation corresponding to the temperature distribution shown in A.

In the opening of Figure 1, Bmin is the width corresponding to the temperature Tmax portion, Bmax is the width corresponding to the temperature Tm1n portion, Bi is the width at the point of distance 11 and temperature Ti, and ΔBi is the difference between Bi and Bmin. be.

FIG. 2 shows the effect of differences in average temperature for each material.

Figure 2 (a) shows that the average temperature of the material is TKI, the average temperature of other materials is TK2, and the difference is ΔTK, and the opening of Figure 2 corresponds to the temperature level shown in Figure 1 (a). The width levels become BKI and BK2, indicating that ΔBK exists in correspondence to ΔTK.

Thus, it can be seen that the trend of material temperature has a strong influence on the variation in the width of the rolled product.

On the other hand, in order to save energy, there is a direct rolling method in which steel slabs obtained by blooming a steel ingot or continuous casting of molten steel are fed into a hot strip mill at a high temperature without being cooled, or the above-mentioned direct rolling method. An operation mode has come to be adopted in which high-temperature steel billets are charged as they are into a heating furnace (hot charge), reheated, and then charged into a hot strip mill.

By the way, when comparing the amount of width variation of the hot strip by the conventional reheating method and the amount of width variation of the hot strip by the direct rolling or hot charging method, the latter has a larger value.

The inventors have elucidated this point and have completed this invention based on the results.

Direct rolling materials and hot charging materials as described above have a larger temperature difference in the material width direction than the conventional reheating method of reheating a steel billet from room temperature.

FIG. 3 shows the temperature distribution in the width direction of the material at the front stage of the finishing mill row when hot rolling a slab using the conventional reheating method.

There is a temperature difference of 15 to 30°C between the center and side edges of the material in the width direction.

In the above-mentioned direct rolling materials and real charge materials, there is a large temperature difference between the center and side edges of the material in the width direction.For example, in the case of direct rolling where the material is sent directly from the blooming mill to the hot strip mill, the temperature difference is 70~70°C. 11
It becomes 0℃.

In terms of width expansion, this will be approximately three times that of the conventional case.

The present inventors have discovered that during rolling of a steel plate, the width expansion of the steel plate mainly occurs at the edges (side edges) of the steel plate (hereinafter referred to as edge portions).
Considering that this is caused by the metal flow of the rolled material, regarding the correlation between the width expansion amount of the rolled material and the material temperature, the temperature at the center in the width direction of the rolled material, the temperature at the edge part, and the temperature at the center part in the width direction of the rolled material and the edge part. As a result of research and elucidation of the temperature difference, the following knowledge, shown in Figure 4, was obtained.

(a) The amount of width expansion of a steel plate is controlled more by the temperature of the edge portion than the temperature of the center portion in the width direction.

(b) Furthermore, to be more precise, it is also controlled by the temperature difference between the widthwise central part and the edge part, as shown in FIG.

In FIG. 4, the horizontal axis shows the bar temperature, the vertical axis shows the total width expansion amount in the rough rolled part, the curve C1 shows the relationship with the edge part temperature, and the dotted line curve C2 shows the relation with the center part temperature of the board width.

In addition, the horizontal axis in FIG. 5 shows the temperature difference between the center part and the edge part, and the vertical axis shows the difference in the amount of width expansion for the uniform temperature material.

Based on these facts, the width accuracy of true charge material or direct rolling material is inferior to conventional reheated material. This is thought to be due to the fact that they have been under control.

The reason why the temperature has conventionally been detected at the center in the width direction of the plate is because the width of the rolled material varies from slab to slab, so the position of the temperature detection end must be changed each time.

With the conventional width control based on temperature measurement at the center in the width direction, it is impossible to reduce the variation in the width of the hot charge material and the direct rolling material to a desired value or less.

The present invention has been made with the object of providing a rolling method that can reduce the variation in the width of rolled products, targeting hot charge materials and direct rolling materials that have large temperature variations in the width direction of the rolled products.

This invention focuses on the temperature of the edge portion of the rolled material, detects the temperature of this portion along the length of the rolled material, and changes the roll opening of the vertical roll stand in response to the temperature change. At the very least, it is necessary to reduce the variation in the width of the final rolled product to an extremely small value, and to detect the temperature difference between the center part in the width direction of the rolled material and the edge part along the length direction of the rolled material, and to detect the edge part. It is characterized by changing the roll opening degree of the rigid roll stand in response to these detected values, thereby reducing the variation in the width of the final rolled product to an extremely small value.

The present invention will be explained in more detail below based on examples thereof.

FIG. 6 shows an apparatus for carrying out the method of controlling the width of a steel plate according to the present invention.

In FIG. 6, RE is a hard roll stand, and RM is a rough rolling mill with horizontal rolls.

TC is a timing device of the rough rolling mill, NC is a rotation speed meter of the rolling rolls of the rough rolling mill, and MV.

MCE is a computing device.

RT E 5 RT C is a temperature detection device, and ENC is a rotation speed meter of a rolling roll on a hard roll stand.

ETC is a timing device for the rigid roll stand, EMV is an integrator, and RES is a rigid roll stand roll opening adjustment mechanism, that is, an operating end.

In order to obtain a rolled material with a uniform width at the stage of rolling from a slab to a sheet bar with a device configured in this way, it is necessary to use the edger RE, the timing devices ETC and TC of the roughing mill installed in the preceding stage, and the respective Rolling mill rotation speed meter ENC
and NC, the time from the start of biting of the rolled material to the completion of rolling in the stand (rolling mill) jE, j
R, roll rotation speeds NE and NR are detected.

These detected values tE, tR2NE, NR, arithmetic device M
VKtR)NR, tE and NE are input to the performance device EIVIV.

The length t of the rolled material is output from each of the calculation devices MV and EMV, and is input to the calculation device MCE.

On the other hand, the temperature Tg at the edge of the rolled material, or the temperature TE at the edge and the temperature T'C at the center in the width direction, are expressed as RTE and RTc.
and inputs the detected value to the arithmetic unit MCE.

In the calculation device MCE, the temperature at the edge portion and the center portion in the width direction in the longitudinal direction of the rolled material is clamped, and the temperature change in the longitudinal direction of the rolled material at the edge portion of the rolled material is calculated as follows: ΔTE1 = TE
i TEmin.

Alternatively, the temperature change in the longitudinal direction of the rolled material at the central part in the width direction of the rolled material Δ'pc i = T'c i TCmin, and further, the temperature change in the longitudinal direction of the rolled material at the central part in the width direction and the edge part of the rolled material Temperature difference ΔT'I)i='pci'r=
i is the amount of calculation.

These calculated values of change ΔTEi, Δ'rc i tΔT
From Di, the width variation ΔRi of the rolled material discharged from the rough rolling mill RM is determined by the temperature change ΔTE at the edge of the rolled material in the longitudinal direction of the rolled material, which is shown by line C1 in FIG.
The amount of width variation due to i, that is, ΔBi−f(ΔTEi
) is calculated by the calculation unit MCE, and then the width fluctuation amount due to the temperature difference ΔTDi at each point in the longitudinal direction of the rolled material between the center part in the width direction of the rolled material and the edge part shown in FIG. 5, that is, ΔBi-f(ΔTCi, ΔTDi)
Wow, calculations are out.

Here, the amount of width variation ΔBi of the rolled material shown in FIG. 5 due to ΔTDi is equal to the amount of temperature change ΔTci in the longitudinal direction of the rolled material at the central part in the width direction of the rolled material, as shown in FIG.
Therefore, ΔBi caused by ΔTDi is calculated according to the measurement result of ΔTcl.

The contribution of ΔTEi calculated in this way and ΔTD
The total width variation amount is calculated by superimposing (adding) the contribution of i.

Next, the arithmetic unit MCE calculates the amount of change in the roll opening degree ΔSi of the endanger RE necessary to eliminate the amount of width variation ΔBi in the longitudinal direction of the rolled material discharged from the rough rolling mill RM.
are calculated from the relationship ΔSi=g(ΔBi), and the results are stored.

Furthermore, the timing device ETC detects the time when the rolled material discharged from the rough rolling mill RM is bitten by the roll of the Edger RE and the passage of time thereafter, and the rotational speed of the hard roll of the Edger RE at the corresponding time. is detected by the ENC, and the detected values tE and NE are input to the integrator EMV, and the integrator EMV calculates the length Eti of the rolled material in the edger RE.
, and input the results to the arithmetic unit MCE.

The arithmetic unit MCFJ stores the memorized position ti (E, ffi conversion value) and El in the longitudinal direction of the rolled material where the width has changed.
When Eti-ti=0, a signal of the required change in the hard roll opening of the edger RE, which is ΔSi, is sent to the roll opening adjustment mechanism RES.

The opening adjustment mechanism RES changes the opening of the edger RE in accordance with the signal.

Furthermore, before the slab is bitten into the first rough rolling mill or ender, the temperature of the edge part or the center part of the rolled material mentioned above is detected, and based on the detection result, the temperature of the edge part in each subsequent pass is detected. , the temperature of the rolled material at the center is determined by heat transfer calculation, and based on this predicted temperature value, the amount of width variation ΔBi in the length direction of the rolled material discharged from the rough rolling mill RM is calculated by the arithmetic unit MCE. Based on the results, a required amount of change ΔSi in the roll opening degree in the edger RE following the rough rolling mill RM is calculated, and the roll opening degree is changed by the roll opening adjustment mechanism RES.

That is, the temperature of the slab before it is bitten by the first rough rolling mill or edger is detected, the detection result is input to the calculation device, and the temperature of the material -T.

Thickness; H6 Width: W.

Length: L.

Transfer time; t.

Input ■ The amount of temperature decrease ΔTr due to radiation is ΔTr= f (To , to ) ■ The amount of temperature decrease ΔTs due to descaling is ΔT8=
f (To, Tw) ■ Temperature rise ΔTM due to plastic working heat generation is ΔTM = f
(Ho t Hl, To , tV ) ■ The amount of temperature decrease ΔTR due to contact with the roll is ΔT R= f (To
, TR2V tld) However, TW; Water temperature Hl: Output plate thickness V: Rolling speed TR; Roll surface temperature td; From the contact arc length, the temperature drop ΔT in each part of the material is calculated as ΔT-To-ΔTR-ΔT8+ΔTM -ΔTR is calculated.

This has the advantage that the temperature detection device, timing device, rotation speed meter, etc. can be installed only in the first stage rough rolling mill and edger in a plurality of stages of rough rolling mills and enders, and the equipment can be simplified.

In addition, in order to more accurately control the width of the rolled material, a width gauge is installed in the middle of the hot strip mill line, and the width of the rolled material is detected as a result of the control, and - the suitability of the control operation is checked. It is also possible to perform so-called feedback control that corrects the control amount for the unrolled portion, and feedforward control that corrects the control amount after the detection section using the width gauge.

Since this invention is constructed and operated as described above, it is possible not only to extremely reduce the variation in the width of rolled products caused by the temperature of the rolled material, but also to reduce the variation in the width of rolled products due to the temperature of the rolled material. Since it is possible to roll a material with a large temperature difference between the center part and the edge part in the material width direction while suppressing the width fluctuation to a small extent, the yield of hot strip products can be improved.

[Brief explanation of the drawing]

Figure 1 is a chart showing changes in temperature and width of rolled material viewed in the length direction of the rolled material, Figure 2 is an explanatory diagram showing average values of temperature and width in the length direction of rolled material, and Figure 3 4 is a chart showing the temperature variation in the width direction of the rolled material, FIG. A chart showing the correlation between the temperature difference at the edge portion and the amount of width expansion, FIG. 6 is an explanatory diagram showing the apparatus for implementing this invention, and FIG. 7 is a graph showing the relationship between the temperature difference ΔTDi and the amount of width expansion. It is. RE...Rigid roll stand, RM...Roughing mill horizontal roll, TC, ETC...Timekeeping device, NC, ENC/
...Revolution meter, MV, MCE...Arithmetic unit, RT E
. RTc...Temperature detection device, EMV...Integrator, RE
S...Roll opening adjustment mechanism.

Claims (1)

[Claims] 1. When hot rolling a slab in a hot strip mill for obtaining steel strip, which has hard rolls in its line that apply a rolling force in the width direction of the material, the input of said hard roll stand The temperature at the side edge of the material is detected by a material temperature measuring device installed on the side, and the detected value is input to a calculation device, and the minimum temperature in the length direction of the steel strip or the average temperature up to that point is calculated from the bending straight line. The calculation device calculates the amount of variation in the width of the steel strip based on the deviation, and calculates the amount of change in the roll opening of the rigid roll stand necessary to erase the calculated width variation amount. A method for controlling the width of a steel plate, characterized in that the width of the steel sheet is controlled by calculating the width of the steel sheet, and also causing a signal to be sent to a roll opening adjustment mechanism of the rigid roll stand to change the roll opening. 2. When hot rolling a slab in a hot strip mill for obtaining steel strip, which has hard rolls in its line that apply rolling force in the width direction of the material, the temperature of the material provided on the entry side of the hard roll stand A measuring device detects the temperature at the side line part of the material and the center part in the width direction of the material, and these detected values are input into a calculation device to calculate the deviation of the temperature at the side edge of the material from the minimum temperature or average temperature in the longitudinal direction of the steel strip. In addition, the temperature deviation between the center part and the side edge part in the width direction of the steel strip (material) at the measurement point is determined, and the amount of width variation of the steel strip based on each temperature deviation is calculated by the calculation device, and the width variation is calculated by using the calculation device. The arithmetic device is caused to calculate the amount of change in the roll opening of the rigid roll stand necessary to erase the calculated value, and a signal is issued to the roll opening adjustment mechanism of the rigid roll stand to determine the roll opening. A method for controlling the width of a steel plate, characterized by changing the width of a steel plate. 3. When rolling a slab in a hot strip mill for obtaining steel strip that has hard rolls in its line that apply rolling force in the secondary direction of the material, the material is rolled in the first horizontal roll stand or before the hard roll stand. Detects the temperature of the side edge, predicts the temperature of the side line of the material at each stage pass based on the detected value, and calculates the deviation from the minimum temperature or average temperature in the length direction of the steel strip using a calculation device. , G (7) The method for controlling the width of a steel plate according to claim 1, wherein the roll opening degree of a rigid roll stand is changed and controlled based on the deviation value.