JPH1194647A - Measuring method and device for temperature of high-temperature steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the mean temperature of a high-temperature steel,even if the surface temperature of the steel plate immediately after cooling greatly differs from the true temperature of the steel or if cooling water or water vapor remains on the steel, and to reduce the facility cost. SOLUTION: Steel plate temperature and cooling water temperature are measured prior to insertion of a steel plate 1 into a cooling device. During cooling, changes in cooling water temperature with time are measured by thermometers 11, 12 for cooling, and the cooling water flow rate is measured, so that the radiation quantity of the steel plate 1 is measured from the temperatures of the cooling water before and after cooling and the cooling water flow rate. From the radiation quantity and the temperature of the steel plate 1 before cooling, the temperature of the steel plate 1 during or after cooling is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the temperature of a high-temperature steel material, and more particularly to a method and an apparatus for measuring the temperature of a steel material during cooling.

[0002]

2. Description of the Related Art Generally, hot-rolled high-temperature steel sheets are:
It is cooled by passing through a cooling device immediately after leaving the finishing mill. Cooling equipment for hot rolled steel plates and steel plates
It is composed of a plurality of banks divided into an upper surface and a lower surface, and the upper surface is cooled by slit laminar or spray, and the lower surface is cooled by jet or spray.

[0003] At this time, if the steel sheet temperature during and after cooling can be measured, the cooling speed and the cooling stop temperature of the steel sheet are predicted, and the sheet passing speed and the cooling water amount are subjected to feedback control. Can be reduced and the yield can be increased. Also,
By making the temperatures of the upper surface and the lower surface of the high-temperature steel sheet coincide with each other during cooling, it is possible to reduce the occurrence of so-called C warpage caused by the temperature difference between the upper and lower surfaces of the steel sheet.

[0004] Although the configuration of the rolling mill and the cooling device are different for the section steel, if the temperature of the steel material during and after cooling can be measured, the passing speed and the amount of cooling water are the same as for the hot rolled steel plate and the thick steel plate. , It is possible to reduce the variation in material, increase the yield, and suppress the occurrence of distortion.

Conventionally, the temperature of a high-temperature steel material has been measured by a surface thermometer. However, if cooling water or water vapor is interposed between the steel material and the surface thermometer, the radiant energy is absorbed and the true temperature can be obtained. Can not. Therefore, various devices have been devised to remove cooling water and water vapor interposed between the steel material and the surface thermometer. Further, the temperature of a steel material is measured in a place where there is no cooling water or steam.

In the past, a method of measuring a steel material temperature after reheating by providing a non-cooling zone in which no cooling is performed in a cooling zone, or measuring a reheating temperature several seconds to several tens of seconds after cooling. The way to be done. In addition, 2-163
As disclosed in Japanese Patent No. 73, a method of measuring the surface temperature of a steel sheet with a surface thermometer while removing cooling water and water vapor with a high-pressure gas has been adopted.

[0007]

However, in a method of providing a non-cooling zone between cooling devices and measuring with a surface thermometer,
Since the steel material rapidly recovers heat in this uncooled region, only the transient surface temperature can be measured, and it is difficult to predict the true temperature (average temperature) of the steel material from the measured temperature. was there. In addition, the provision of the non-cooling zone causes a decrease in the cooling rate of the steel material.

A method of measuring the reheating temperature several seconds to several tens of seconds after cooling is to install a surface thermometer on the rear surface of the cooling device, and measure the temperature after cooling is completed and reheating is performed. Is what you do. However, the time to actually complete recuperation is
It differs depending on the thickness of the steel material and the cooling conditions. When the steel material passes through the installation position of the surface thermometer, the steel material may be in the middle of recuperation or in the middle of the completion of the recuperation and the temperature of the steel material may be decreasing. Therefore, even in this method, it was difficult to predict the true temperature (average temperature) of the steel material from the steel sheet surface temperature.

Further, in these methods, there is also a problem that the temperature history during cooling of the steel material is unknown, and it is difficult to control the temperature of the steel material by feedback because the determination of the excess or deficiency of the cooling is delayed.

In the method in which cooling water and water vapor are removed by a high-pressure gas and measured by a surface thermometer, it is difficult to remove the cooling water when a large amount of cooling water is present. Was difficult to measure. The surface temperature of steel that can be measured during cooling is
It is a lower value than the average temperature of steel material, which is a management item in operation and has a meaning in quality control. Therefore, information on the cooling rate and the cooling stop temperature cannot be obtained directly. Further, when there are a plurality of cooling devices, it is necessary to install a large number of expensive surface thermometers in order to measure the temperature of the steel material in each cooling bank, resulting in an increase in equipment costs.

As described above, in the prior art, it was difficult to measure the average temperature of the steel material during cooling.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. In cooling a high-temperature steel material with cooling water, particularly, the surface temperature immediately after cooling such as the cooling of a thick steel plate and the true temperature of the steel material. The average temperature of high-temperature steel can be measured accurately, even when the temperature is significantly different from (steel center temperature or average temperature), and even when cooling water or steam stays on the steel. An object of the present invention is to provide an inexpensive high-temperature steel material temperature measuring method and apparatus.

[0013]

According to a first aspect of the present invention, there is provided a method for measuring the temperature of a high-temperature steel material, comprising: injecting a fluid into the steel material; A method for measuring a temperature of a high-temperature steel material, wherein a temperature of the steel material is obtained from a flow rate of the fluid and a change in temperature.

By measuring the flow rate and temperature change of the fluid injected into the steel material, the amount of heat transferred from the steel material to the fluid can be measured. Then, the temperature (average temperature) of the steel material can be obtained from the calorific value and the steel material temperature before the fluid is injected.

[0015] A second means for solving the above-mentioned problems is as follows.
A step of measuring the temperature of the high-temperature steel material before being conveyed to the cooling device, and a step of measuring the temperature of the cooling water before being supplied to the cooling device and the temperature of the cooling water after cooling the steel material to obtain a rise in the temperature of the cooling water And the step of determining the flow rate of the cooling water, determining the heat removal amount of the steel material from the flow rate of the cooling water and the temperature rise, and calculating the steel material temperature from the heat removal amount and the temperature of the high-temperature steel material before being conveyed to the cooling device. A method for measuring the temperature of a high-temperature steel material, comprising calculating an average temperature of the high-temperature steel material during or after cooling, wherein the temperature of the cooling water during the temperature measurement of the high-temperature steel material is 80 ° C or less. A method for measuring the temperature of a high-temperature steel material, wherein the temperature at the start of cooling of the high-temperature steel material is 1000 ° C. or less (Claim 2).

If the flow rate and temperature rise of the cooling water are determined, the amount of heat transferred from the steel material to the fluid can be determined. And
The temperature (average temperature) of the steel material can be determined from the heat quantity and the temperature of the high-temperature steel material before being conveyed to the cooling device.

At this time, if the temperature of the cooling water during the temperature measurement of the high-temperature steel material exceeds 80 ° C., a large amount of steam is generated, and the accuracy of the temperature measurement by the present method deteriorates due to the influence of the heat of evaporation. The application range of the cooling water during the temperature measurement of high-temperature steel
It is limited to the case where the temperature is 0 ° C. or lower. In addition, since the same problem occurs when the temperature at the start of cooling the high-temperature steel exceeds 1000 ° C., the applicable range of the present method is limited to the case where the temperature at the start of cooling the high-temperature steel is 1000 ° C. or lower. I do.

A third means for solving the above-mentioned problem is as follows.
A device for measuring the temperature of a high-temperature steel material when cooling the high-temperature steel material online, means for measuring the temperature of the steel material before cooling, means for measuring the flow rate of cooling water during cooling, and cooling before cooling. Means for measuring the water temperature, means for measuring the cooling water temperature after cooling, and calculating the amount of heat deprived from the steel material from the cooling water flow rate during cooling, the cooling water temperature before cooling and the cooling water temperature after cooling. A temperature measuring device for a high-temperature steel material, comprising: calculating means for calculating the temperature of the steel material during or after cooling from the temperature of the steel material before cooling and the amount of heat taken from the steel material. Claim 3).

According to this apparatus, since the invention described in claim 2 can be carried out, the temperature (average temperature) of the steel material after or during cooling can be accurately obtained. It is to be noted that a microcomputer may be used as each calculation means, and a specific calculation expression may be, for example, a calculation expression which will be described later in the embodiments and examples of the invention. As temperature measurement means and flow rate measurement means,
Known ones can be appropriately selected and used.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an example of an embodiment in which the present invention is applied to a cooling device for a thick steel plate. As shown in FIG. 1, ten pairs of restraining rolls 2, 3 are provided above and below the high-temperature steel plate 1 at a pitch of 1000 mm, and a cooling bank is provided between each pair of restraining rolls 2, 3. . The steel plate upper surface is cooled by the upper surface slit nozzle 4 and the steel plate lower surface is cooled by the circular tube laminar nozzle 5 with the lower surface conduit. The steel sheet surface temperature of the high-temperature steel sheet 1 is measured by an entrance-side surface thermometer 6 provided on the cooling-device entrance side, and the average temperature of the high-temperature steel sheet 1 is determined from the surface temperature. The average temperature of the cooling water is also measured in advance.

FIG. 2 shows details of the cooling device. An upper surface slit nozzle 4 is provided on the upper surface side of the steel sheet between each pair of the constraint rolls 2 and 3 from the upstream roll to the downstream roll in the steel sheet transport direction, and cooling water is stored on the lower surface side of the steel plate. Bottom tank 8 is arranged. As a lower cooling nozzle, five rows of circular pipe nozzles 9 are provided in the water in the lower tank 8 at a pitch of 100 mm in the width direction of the steel sheet in the conveying direction of the steel sheet, and are provided above each circular pipe toward the lower surface of the steel sheet. A tube laminar nozzle 5 with a lower surface conduit comprising a conduit 10 is provided. The upper surface of the steel plate is cooled by injecting a predetermined amount of cooling water from an upper surface slit nozzle 4 provided on the upper surface side of the steel plate to the high temperature steel plate 1 continuously transferred in such a cooling device, and By jetting water from a circular tube laminar nozzle 5 with a lower surface conduit provided at the lower surface, the lower surface is cooled by a liquid flow generated by the accompanying flow. On the lower surface, the cooling water returns to the lower surface tank 8 and is accompanied again.

The cooling water injected from the upper and lower nozzles exchanges heat between the steel plate and the cooling water, and the cooling water temperature rises by the amount of heat lost by the steel plate. Therefore, as shown in FIG. 2, one or a plurality of thermometers 11 are disposed downstream of the upper surface slit nozzle 4 on the upper surface side so as to be submerged in the upper surface cooling water, and the lower surface side on which the cooling water is stored is provided on the lower surface side. By installing one or more thermometers 12 in the tank 8, the temperature of the cooling water that has risen from the previously measured initial temperature of the cooling water is determined.

Here, the amount of heat exchanged between the cooling water and the steel plate is Qupper = ρw · Cw · W1 · w · L · τ · ΔTw1 (1) Qlower = ρw · Cw · W2 · w・ L ・ τ ・ ΔTw2 ... (2) where, Qupper: Heat removal from upper surface [J] Qlower: Heat removal from lower surface [J] ρw: Cooling water density [kg / m ³ ] Cw: Cooling water specific heat [ J / kgK] W1: Upper surface cooling water volume density [m ³ / m ² sec] W2: Lower surface cooling water volume density [m ³ / m ² sec] w: Steel plate width [m] L: Cooling bank length [m ] τ: Cooling time [sec] ΔTw1: Upper surface cooling water temperature rise [K] ΔTw2: Lower surface cooling water temperature rise [K]

The amount of heat removed from the steel sheet is as follows: Qout = ρs · Cs · ΔTs · w · L · d (3) where, Qout: heat removal amount from the steel sheet [J] ρs: density of the steel sheet [kg / m ³ ] Cs: Specific heat of the steel sheet [J / kgK] ΔTs: Temperature drop amount of the steel sheet (= Ts−Ts') [K] d: Sheet thickness [m], which is given by the formulas (1), (2), and (3) Is based on the following equation. Qout = Qupper + Qlower… (4)

The following equation can be derived from this relationship. Ts ′ = Ts−ρw · Cw · (W1 · ΔTw1 + W2 · ΔTw2) · τ / (ρs · Cs · d) (5) Ts ′: Average temperature of the steel sheet at the bank exit side [K] Ts: Steel sheet at the bank entry side Average temperature [K]

Therefore, by using the expression (5), the average temperature of the steel sheet at the bank exit side can be obtained from the average temperature of the high-temperature steel sheet measured by the entrance-side surface thermometer 6 on the entrance side of the cooling device. When there are a large number of banks, the average temperature of the steel sheets on the exit side of each bank can be obtained by sequentially measuring the average temperature of the steel sheets of the preceding bank as the average temperature on the entrance side of the subsequent bank from the preceding bank.

In order to quantitatively evaluate the equation (5) derived from the above, only the uppermost bank with respect to the passing direction of the cooling device shown in FIG. 1 has an upper surface cooling water amount of 0.033 m ³ / m ² sec. Then, a lower surface cooling water amount of 0.02 m ³ / m ² sec was injected, and a steel plate having a width of 1000 mm, a length of 5 m, and 850 ° C. was actually passed while changing the thickness and passing time of the cooling bank. At this time, the surface thermometer 13 is installed on the downstream side of one bank in the cooling device to measure the surface temperature of the steel sheet immediately after cooling. In addition, the cooled steel plate
The sheet was conveyed to a position directly below the outlet-side surface thermometer 7 installed on the rear surface of the cooling device, and after waiting until the steel sheet temperature was sufficiently recovered, the steel sheet surface temperature was measured.

The measurement results are shown in Table 1 and FIG. In FIG. 3, the horizontal axis represents the temperature measured by the outlet-side surface thermometer 7 after waiting until the steel plate temperature has sufficiently recovered, and the vertical axis represents the temperature obtained from the increase in the cooling water temperature according to the present invention. The temperature obtained by the surface thermometer 13 is shown. According to Table 1 and FIG. 3, the steel sheet surface temperature immediately after cooling measured by the surface thermometer 13 and the surface temperature of the steel sheet after sufficiently recuperating by the outlet-side surface thermometer 7 are greatly different from each other. It can be seen that the average temperature of the steel sheet cannot be predicted by the measurement with the meter. Further, the average temperature of the steel sheet obtained from the rise of the cooling water temperature according to the present invention (“calculated value” in Table 1)
Is almost the same as the temperature measured by the outlet-side surface thermometer 7.

[0029]

[Table 1]

As described above, according to the present invention, the average temperature of the steel sheet can be measured even when the surface temperature of the steel sheet immediately after cooling is lowered. That is, when cooling the high-temperature steel sheet, by calculating the heat removal amount of the high-temperature steel sheet from the rise of the cooling water temperature on the upper surface and the lower surface, the average temperature of the steel sheet for each cooling bank is measured using the equation (5). Can be.

[0031]

【Example】

(Embodiment 1) Next, an embodiment in which the present invention is applied to a thick steel plate will be described.

The cooling device shown in FIG. 1 and FIG.
8m, length of 20m, thickness of 30mm, hot rolled steel plate with initial temperature of 850 ℃ passed through 40mpm, and 0.033m ³ / m ² sec of cooling water flowed from the upper slit nozzle 4 to the upper surface of the steel plate. , 0.02m ³ /
Cooling was performed by injecting m ² sec of cooling water toward the lower surface of the steel sheet. At the same time, the temperature was measured by the surface thermometers 6 and 7 before the high-temperature steel sheet was conveyed to the cooling device and after the high-temperature steel plate came out of the cooling device.

Table 2 shows the relationship between the rise in cooling water temperature in each cooling bank and the average temperature of the steel sheets (calculated from the rise in cooling water temperature). When the temperature of the steel sheet immediately after leaving the cooling device was measured by the exit side surface thermometer 7, 23
Although the temperature was as low as 0 ° C., the temperature gradually recovered and showed a peak temperature of 452 ° C. after about 30 seconds, and then the temperature was gradually lowered after cooling. The average temperature of the steel sheet obtained from the rise in the cooling water temperature was 463 ° C as shown in Table 2.
And almost coincides with the peak temperature of 452 ° C.

[0034]

[Table 2]

Since the peak temperature is considered to be the temperature when the recuperation is completed and the entire steel plate becomes a uniform temperature, the peak temperature may be considered to be the average value of the steel plate temperature after cooling. Therefore, it was confirmed that a temperature almost consistent with this was obtained by the method of the present invention.
This shows that the steel plate temperature could be measured with high accuracy. Further, when the hardness of the steel sheet after cooling and the hardness of the test piece cooled in the laboratory based on the temperature history in Table 2 were compared, they almost agreed, and the temperature history of the steel sheet obtained from the temperature rise of the cooling water was It turned out to be correct, and the average steel sheet temperature in each bank could be measured online.

In the present embodiment, a cooling apparatus using a slit nozzle on the upper surface and a circular laminar nozzle with a lower conduit on the lower surface has been described as a cooling method. However, the method of the present invention can be applied to other cooling methods such as spray cooling, Needless to say, the present invention can be applied to a laminar tube cooling, a flat laminar cooling, a slit jet cooling, and the like. Further, in the present embodiment, an example in which the present invention is applied to a thick steel plate is shown, but the present invention is similarly applicable to a thin steel plate.

In order to measure the temperature of the cooling water after cooling, it is particularly necessary to measure the cooling of the lower surface so that the cooling water after cooling does not escape. For example, as shown in FIG. 4, when spray cooling by the spray nozzle 14 is employed for lower surface cooling, a tray or a water tank 15 for receiving falling cooling water is provided, and the temperature of the cooling water therein is measured by a cooling water thermometer. It is better to measure at 12.

As for the cooling of the upper surface, the temperature of the cooling water after cooling is measured, for example, by installing a tray or a water tank 15 for catching the cooling water staying on the steel plate or the cooling water falling from the steel plate as shown in FIG. Then, the temperature may be measured by the thermometer 11 for cooling water. In the case where cooling is continuously performed while constrained by a draining roll, as shown in FIG. 6, a cooling water thermometer 11 is attached to the draining roll (top-restricted roll) 2, and the temperature of the cooling water blocked by the draining roll is measured. It is effective to measure

(Embodiment 2) In a second embodiment, the temperature measuring method of the present invention is applied to a steel plate immersion cooling apparatus.
This embodiment will be described with reference to FIG.

In the present embodiment, the hot steel sheet 1 after rolling is submerged in a water tank 16 to which cooling water is continuously supplied by an elevating device, and is cooled by a submerged cooling device that performs cooling while forcibly stirring with a jet flow. It is possible to monitor the temperature. The cooling water is continuously sent to the jet nozzle 17 in the water tank by the cooling water supply pump, and is jetted near the high temperature steel plate 1. The temperature and flow rate of the supplied cooling water are measured before being supplied to the water tank. After rolling, the hot steel sheet is immersed in a water tank by a steel sheet elevating device from a transfer table. The cooling water continuously draws heat from the upper and lower surfaces of the steel plate, overflows from the upper portion of the water tank, and flows out from the drain pipe 18. At this time, the temperature of the cooling water flowing out is continuously measured by the cooling water thermometer 19. In this embodiment, the temperature change of the cooling water flowing out appears with a certain time delay from the time when the steel sheet is immersed in the water tank.

Assuming that the temperature of the water tank before the start of cooling is T ₀ and the temperature of the water tank T ₁ in the steady state during cooling is a time change of the water temperature T of the water tank.
Assuming that the cooling water in the water tank is completely mixed instantaneously, it is expressed by the following equation. T = (T ₁ −T ₀ ) (1−exp (−W′τ / S)) + T ₀ (6) where, S: internal volume of water tank [m ³ ] W ′: flow rate of supply cooling water [ m ³ / s]

ΔT = T ₁ −T ₀ is the temperature rise of the cooling water, and the heat quantity Q deprived of the steel sheet per unit time is obtained from the following equation. Q = ρ · Cw · W ′ · ΔT (7) where, Q: heat amount deprived from the steel sheet [J / s] Cw: specific heat of water [J / kgK] ρ: density of water [kg / m ^3] ]

Accordingly, it is possible to estimate the temperature drop amount of the steel sheet from the equation (7), and it is possible to accurately know the steel sheet temperature that changes every moment. Immediately after the steel sheet is submerged in the water tank, a certain time delay appears in the change in cooling water temperature as is clear from equation (6), but the change over time can be predicted because the internal volume and flow rate of the water tank are known. It is.

Using the cooling device shown in FIG. 7, the steel plate immediately after rolling was 2.0 m in width, 10 m in length, 240 mm in thickness, and the temperature of the steel plate.
The material having a temperature of 1020 ° C. was immersed in a water tank having a water temperature of 20 ° C. and an internal volume of 30 m ³ to perform cooling. The cooling water flow rate is 2.0 m ³ /
s, the water temperature was 20 ° C. as the water tank temperature.

At this time, the cooling water temperature reached the peak value of 42 ° C. in about 50 seconds. From this, the amount of heat deprived from the steel sheet can be estimated to be 186480 KJ / s by applying equation (7). As a result, the average temperature drop curve is expected as shown in FIG.

FIG. 8 is a diagram showing the actual value of the temporal change in the cooling water temperature and the predicted value predicted by the equation (6), with the horizontal axis representing time and the vertical axis representing the temperature change of the cooling water. . Referring to FIG. 8, it can be seen that the actual value and the predicted value are in good agreement, and that equation (6) is correct. The amount of heat deprived from the steel sheet can be obtained using the water temperature rise at the time when the water temperature change stops from the start of cooling.

Since the target cooling stop temperature of the steel sheet is 550 ° C., the cooling time can be determined to be 65 seconds from FIG. 9, and the steel sheet was taken out of the water tank at this time. After the surface temperature was sufficiently recovered, the temperature of the steel sheet was measured by a surface thermometer and found to be 545 ° C. From this, the steel sheet temperature measuring method of the present invention is accurate and its effectiveness is clear.

(Embodiment 3) This embodiment is an example in which the temperature is measured in a submerged immersion jet type cooling apparatus of a continuous annealing apparatus for thin steel sheets.

As shown in FIG. 10, the sheet thickness continuously fed from the continuous annealing furnace to a 4.0 m high underwater immersion type cooling device was obtained.
A thin steel plate 20 having a thickness of 2 mm and a width of 1200 mm is introduced into the water-cooling device 21 from directly above at a speed of 600 mpm, the direction is changed by a roll 22 installed in the water-cooling device, and is continuously sent directly above.
It is sent to the overage treatment zone in the cooling process. In this underwater immersion type cooling device, cooling water is supplied from a perforated plate-type cooling header provided on both surfaces of a steel plate, and the cooling water constantly collides with both surfaces of the thin steel plate. The flow rate of the cooling water supplied in the cooling device is adjusted via a flow rate adjusting valve, and the flow rate is measured by an electromagnetic flow meter. The temperature of the cooling water is also continuously measured by a thermocouple.

The cooling water after cooling the steel sheet flows from the gap between the cooling header of the perforated sheet and the steel sheet to the end of the sheet, and is then drained from the cooling drain pipe. At this time, the temperature of the cooling water is measured by a thermometer.

The inlet temperature of the cooling device for the thin steel plate was 780 ° C. as measured by a surface thermometer. Water volume density of cooling water is 0.0
2 m ³ / m ² sec, the cooling water temperature at the inlet was 22.5 ° C., and the cooling water temperature at the drain pipe was 34.4 ° C. When calculated from these values using the method of the present invention, the temperature of the thin steel sheet at the outlet of the cooling device was 602 ° C. Actually, when the temperature was measured with the surface thermometer 23 at a position 5 m above the cooling device, 631
° C.

As described above, by using the method of the present invention, it is possible to know the temperature of the steel sheet without providing a temperature measuring means such as a surface thermometer. Actually, the steel sheet surface after cooling is wet with cooling water or covered with water vapor, so temperature measurement has been very difficult so far, and it has been difficult to know the temperature at the end of cooling. According to this, it is possible to easily and accurately know the steel plate temperature.

(Embodiment 4) In a fourth embodiment, the steel sheet temperature measuring method of the present invention is applied to a flange temperature measuring method for an H-section steel.

The flange side guides provided on the front and rear surfaces of the rough rolling mill incorporate a perforated water cooling device with a length of 10 m. Cooling. The cooling water is sent by a cooling water pump, and after measuring the flow rate and the water temperature, it is sent to a perforated cooling nozzle via an electromagnetic valve, and the cooling water is supplied and injected only when the rolled material passes. . After cooling, the cooling water is replenished in a water collection pit below the side guide, the temperature is measured, and then drained.

In this cooling device, a size of 500 mm × 500
The H-section steel immediately after rolling having a flange thickness of 80 mm, a web thickness of 60 mm and a length of 20 mm was continuously cooled. The rolling speed was 120 mpm, and the flange outer surface temperature immediately before rolling was 1050 ° C. The supplied cooling water temperature is 20 ° C, and the cooling water flow rate is
0.015m ³ / m ² sec per unit area of H-section steel flange outer surface
It is. The cooling water temperature measured at the water collection pit was 39.5 ° C.

At this time, when the rolled material passes through a cooling zone of 10 m in total of 10 m on the front surface and 10 m on the rear surface of the rolling mill at 120 mpm (that is, cooling time of 10 seconds), the amount of heat taken per unit area of the outer surface of the flange is given by the following equation. It is possible to ask. q = ρw · Cw · W · ΔT (8) where, q: heat flow (heat flux) deprived per unit area [J / m ² s] ρw: cooling water density [kg / m ³ ] W: Flow rate of cooling water supplied per unit area (water density) [m ³ / m ² s] Cw: Specific heat of cooling water [J / kgK] ΔT: Temperature rise of cooling water [K]

When the above-mentioned numbers are applied to equation (8) and calculated, q is 1229 kJ / m ² s. Correspondingly, the average temperature of the H-section flange is expected to drop at 3.1 ° C / sec. In fact, this mill passed through 11 passes (rolling time about 5
Minutes, cooling time 110 seconds), and then the temperature was recovered and the flange temperature was measured with a surface thermometer. As a result, the temperature was 711 ° C., which almost coincided with 709 ° C. determined by the present invention.

As described above, the temperature measuring method according to the present invention is capable of accurately knowing the steel material temperature during and after cooling in a short time, as compared with the conventional method of determining the steel sheet temperature from the steel sheet surface temperature after reheating. Obviously, it is an excellent temperature measurement method. Furthermore, if this method is combined with a temperature control method as an online temperature measurement method, dynamic and high-precision steel temperature control is possible.

(Comparative Example) As a comparative example of the present invention, an example is shown in which, in the same cooling device as in the first embodiment, cooling water and water vapor are removed by high-pressure gas and the surface temperature of the steel sheet is measured by a surface thermometer.

As shown in FIG. 11, optical fiber thermometers 24 were installed on the upper and lower surfaces of a steel plate in each bank of the cooling device. As shown in FIG. 12, the distal end of the optical fiber thermometer is configured such that high-pressure air can be jetted from an air supply pipe 25 provided around the optical fiber light receiving unit 25.
The structure is such that cooling water and water vapor staying on the steel plate can be removed by high-pressure air.

This cooling device had a sheet width of 2.8 as in Example 1.
m, plate length 20m, plate thickness 30mm, hot rolled steel plate with initial temperature of 850 ° C passed through at 40 mpm, and 0.033m ³ / m ² sec of cooling water flowed from the upper slit nozzle 1 to the upper surface of the steel plate. , 0.02m ³ /
Cooling was performed by injecting m ² sec of cooling water toward the lower surface of the steel sheet. At the same time, with surface thermometers 6 and 7,
The temperature was measured before the high-temperature steel sheet was conveyed to the cooling device and after the high-temperature steel sheet came out of the cooling device.

The temperature of the steel sheet after leaving the cooling device was measured by the surface thermometer 7 to be 246 ° C. Table 2 shows the optical fiber thermometer readings in each bank at this time.
This is shown as “Steel sheet temperature / Comparative example”. FIG. 6 shows the temperature in each bank of the steel plate temperature obtained in the example and the temperature actually measured in the comparative example. In the comparative example, what can be measured is the surface temperature of the steel sheet, and has no relation to the average temperature of the steel sheet required as the actual temperature in operation. In addition, the temperature indication values in each bank vary greatly because the cooling water staying on the upper surface of the steel sheet cannot be completely eliminated. For this reason, it is very difficult to predict the average temperature of the steel sheet by measuring the surface temperature of the steel sheet.

[0063]

As described above, according to the present invention, in the method for measuring the temperature of a high-temperature steel material, a fluid is injected to the steel material, and the temperature of the steel material before the fluid is injected, and the flow rate and the temperature of the fluid injected to the steel material. Since the temperature of the steel is obtained from the change, the average temperature of the high-temperature steel can be accurately measured.

In particular, the step of measuring the temperature of the high-temperature steel material before being conveyed to the cooling device, and measuring the temperature of the cooling water before supplying it to the cooling device and the temperature of the cooling water after cooling the steel material, and A step of obtaining a temperature rise, and a step of obtaining a flow rate of cooling water, obtaining a heat removal amount of the steel material from the flow rate and the temperature rise of the cooling water, and obtaining a heat removal amount of the high-temperature steel material before being transferred to the cooling device. A method for measuring the temperature of a high-temperature steel material, comprising calculating an average temperature of the high-temperature steel material during or after cooling by calculating a steel material temperature from the temperature, wherein a temperature of the cooling water during the temperature measurement of the high-temperature steel material is determined. According to the method for measuring the temperature of a high-temperature steel material at 80 ° C. or lower and the temperature at the start of cooling of the high-temperature steel material at 1000 ° C. or less, the average temperature of the high-temperature steel material during cooling can be measured. Can be judged instantaneously and accurate It is possible to perform the cooling control.
As a result, variation in the quality of the steel material is reduced, and the yield is improved. In addition, since the steel sheet temperature can be measured quickly, the rolling efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a cooling device to which the present invention is applied.

FIG. 2 is a schematic diagram showing an example of an embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a temperature of a steel sheet after cooling obtained from a temperature change of cooling water and a value measured by a surface thermometer after sufficient heat recovery in Example 1.

FIG. 4 is a schematic view showing an example in which the present invention is applied to lower surface spray cooling of a high-temperature steel sheet.

FIG. 5 is a schematic view showing an example in which the present invention is applied to upper surface spray cooling of a high-temperature steel sheet.

FIG. 6 is a schematic diagram showing an example in which the present invention is applied to an upper surface cooling facility in which a high-temperature steel plate is constrained by a drain roll.

FIG. 7 is a schematic view of an immersion cooling device according to a second embodiment of the present invention.

FIG. 8 is a diagram showing a change over time in temperature rise of cooling water in Example 2.

FIG. 9 is a diagram showing a change with time of a steel sheet temperature obtained from a rise in cooling water temperature in Example 2.

FIG. 10 is a schematic diagram of a submerged immersion jet type cooling device of a continuous annealing device in Embodiment 3 of the present invention.

FIG. 11 is a view showing a state of installation of a surface thermometer used in a comparative example.

FIG. 12 is a schematic diagram of a light receiving unit of the surface thermometer used in the comparative example.

FIG. 13 is a diagram showing the temperature in each bank of the steel sheet measured in Example 1 and Comparative Example.

[Explanation of symbols]

 1-High temperature steel plate 2-Upper surface constraining roll 3-Lower surface constraining roll 4-Upper surface slit nozzle 5-Circular tube laminar nozzle with lower surface conduit 6-Incoming surface thermometer 7-Outer surface thermometer 8-Lower surface tank 9-Circular tube Nozzle 10-Conduit 11-Cooling water thermometer 12-Cooling water thermometer 13-Cooling zone surface thermometer 14-Spray nozzle 15-Water collecting tank 16-Water tank 17-Jet nozzle 18-Drain pipe 19-Cooling water temperature 20-Thin steel plate 21-Water cooling device 22-Roll 23-Surface thermometer 24-Optical fiber thermometer 25-Optical fiber light receiving part 26-Air supply pipe

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Masato Uchio 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Kokan Co., Ltd. (72) Inventor Kazuya Fukuoka 1-2-1, Marunouchi, Chiyoda-ku, Tokyo No. Nippon Kokan Co., Ltd. (72) Inventor Takayuki Nakanishi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (3)

[Claims] 1. A method for measuring a temperature of a high-temperature steel material, wherein a fluid is injected to the steel material, and the temperature of the steel material is obtained from a temperature of the steel material before the fluid is injected, a flow rate of the fluid injected to the steel material, and a temperature change. Temperature measurement method for high temperature steel. 2. A step of measuring the temperature of the high-temperature steel material before being conveyed to the cooling device, and measuring the temperature of the cooling water before supply to the cooling device and the temperature of the cooling water after cooling the steel material. A step of obtaining a temperature rise, and a step of obtaining a flow rate of cooling water, obtaining a heat removal amount of the steel material from the flow rate and the temperature rise of the cooling water, and obtaining a heat removal amount of the high-temperature steel material before being transferred to the cooling device. A method for measuring the temperature of a high-temperature steel material, comprising calculating an average temperature of the high-temperature steel material during or after cooling by calculating a steel material temperature from the temperature, wherein a temperature of the cooling water during the temperature measurement of the high-temperature steel material is determined. A temperature measuring method for a high-temperature steel material having a temperature of 80 ° C. or less and a temperature at the start of cooling of the high-temperature steel material of 1000 ° C. or less. 3. An apparatus for measuring the temperature of a high-temperature steel material when cooling the high-temperature steel material online, comprising: means for measuring the temperature of the steel material before cooling; and means for measuring the flow rate of cooling water during cooling. Means for measuring the temperature of the cooling water before cooling, means for measuring the temperature of the cooling water after cooling, and the flow rate of the cooling water during cooling, the temperature of the cooling water before cooling, and the temperature of the cooling water after cooling. A high-temperature steel material comprising: arithmetic means for calculating the heat quantity of the steel material; and arithmetic means for calculating the temperature of the steel material during or after cooling from the temperature of the steel material before cooling and the amount of heat deprived from the steel material. Temperature measuring device.