JPS61173123A - Correcting method of emissivity of radiation thermometer - Google Patents

Abstract

PURPOSE:To correct exactly the emissivity of a radiation thermometer by obtaining an emissivity correction value from the temp. at the transformation point of a measuring object and the temp. when the change of the temp. rising speed of the measuring object slows down and using the same as the correction set value of the measuring temp. CONSTITUTION:The temp. at the transformation point where the crystal structure of a steel plate 17 or the like changes is first known from the components of said steel plate and is determined as the true temp. of the steel plate 17 in the stage of measuring the temp. in a furnace such as continuous annealing furnace for the steel plate 17, etc. by using the radiation thermometer. The steel plate 17 is gradually heated and the temp. thereof is measured by a temp. sensor 32. The emissivity correction value is determined in an emissivity correction circuit 34 from the temp. when the change of the temp. rising speed thereof slows down and the temp. at the transformation point which is the true value. The value is then outputted from a correction setting part 31 and the true temp. is obtd. as the correction value of the measuring temp. The exact measurement is thus made possible by making use of the actual operating conditions in the actual furnace without requiring special apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in an emissivity correction method for a radiation thermometer.

[Technical background of the invention]

Generally, in a continuous annealing furnace for steel sheets, a radiation thermometer is used to measure the temperature inside the furnace. To measure the correct steel plate temperature using this radiodensitometer, accurately measure the emissivity of the steel plate, set an emissivity correction value based on this, and then apply the emissivity correction value to the temperature measured by the radiation thermometer. It is necessary to obtain the true value of temperature by correcting it.

Therefore, conventionally, as a means of determining the emissivity of a steel plate, the true temperature of the steel plate is measured with a contact thermometer other than a radiation thermometer, and at the same time, a radiation thermometer is also used to measure the true temperature of the steel plate.
Measures are taken to calculate an emissivity correction value such that the measured value of the radiation thermometer becomes the same temperature as the true concentration.

However, the emissivity of a steel plate is affected by the oxidation state of the steel plate surface and the wavelength band used by the radiation thermometer, so if the furnace conditions differ or the type of radiation thermometer used differs, the emissivity will also change. It will be different. Therefore, in order to obtain the correct emissivity correction value, it is necessary to obtain the emissivity correction value of the steel plate by realizing the conditions of the furnace using experimental equipment, or to obtain the emissivity correction value of the steel plate in an actual furnace. Must be.

[Problems with background technology]

However, when using the former method to obtain emissivity correction values, it is actually very difficult to create experimental equipment under the same conditions as an actual reactor, and in the end, it is difficult to obtain accurate emissivity correction values. I can't. On the other hand, in the latter method of determining emissivity using an actual furnace, it is difficult to determine the true steel/plate temperature because the steel plate is actually moving. In addition, as a method of measuring the temperature of a moving steel plate, as shown in Fig. 5, the contact thermometer 2 is brought into contact with the surface of the moving steel plate 1, but since the steel plate 1 is moving, Since the condition is poor and frictional heat is generated, accurate emissivity correction values cannot be obtained. Therefore, it is conceivable to stop the running of the steel plate 1 and measure the temperature using the contact thermometer 2, but since the surface condition of the steel plate 1 and the steel plate temperature are constantly changing, it is also possible to use accurate emissivity correction. I can't get the value. 3 indicates the furnace wall.

As described above, the conventional means for determining the emissivity correction value cannot accurately determine the emissivity correction value of a radiation thermometer installed to measure the temperature of a steel plate in a continuous blunt furnace or the like.

(Objective of the Invention) The present invention has been made with attention to the above-mentioned points. Therefore, the emissivity correction value of the radiation thermometer is easily and accurately determined by taking advantage of the actual operating conditions in an actual reactor, and this correction value is The present invention provides an emissivity correction method for a radiation thermometer that accurately measures the temperature of an object to be measured.

[Summary of the invention]

In the present invention, the transformation point temperature of the object to be measured is known in advance, the object to be measured is gradually heated in an actual furnace using actual operating conditions, and the portion where the temperature increase rate slows down is found. This is an emissivity correction method for a radiation thermometer in which an emissivity correction value is obtained from the transformation point temperature, which is the true value, and is used as a correction set value for the measured concentration.

[Embodiments of the invention]

First, there is a problem in how to find the true temperature of a steel plate running in an actual furnace. Therefore, the present inventors focused on the structure of the object to be measured, for example, iron. 1. Iron has a transformation point where its crystal structure changes depending on temperature. At this transformation point, as shown in FIG. 1, the specific heat increases rapidly at a certain temperature. For example, in the case of a steel plate, once the composition of the steel plate is determined, this transformation point temperature remains constant regardless of the surface condition. Therefore, by using the transformation point temperature, the true steel plate temperature can be determined. .

Therefore, the method of the present invention is to obtain the emissivity correction value of the radiodensitometer in an actual furnace using the above-mentioned transformation point temperature, and the outline thereof will be explained below with reference to FIG. Explain the configuration.

In this annealing furnace, a heating zone 11, a soaking zone 12, an overaging zone 13, and a final cooling zone 14 are arranged in this order, and a cooling zone 15 is provided between the soaking zone 12 and the overaging zone 13. It is designed to cool the steel plate. Then, the steel plate 17 is fed out from the payoff reel 16.
is first supplied to the heating zone 11 through the cleaning tank 18, where the steel plate 17 is gradually heated to a desired temperature. Although the heating means in this case is not shown, a predetermined number of burners are arranged along the steel plate conveying path of the heating zone 11, and heating is performed by controlling these burners. At this time, a radiation thermometer 19 is provided between the heating zone 11 and the soaking zone 12 to measure the temperature of the steel plate 17.

The half 20 is a louver, 21 is a temper rolling mill, and 22 is a tension reel.

Next, an embodiment of the method of the present invention will be described.

First, once the composition of the steel plate 17 is determined, the transformation point temperature of the steel plate 17 is determined. Therefore, if the transformation point temperature of the steel plate 17 is known in advance, this can be determined as the true temperature of the steel plate 17.

Therefore, after knowing the transformation point temperature of the steel plate 17 as described above, the steel plate 17 fed out from the payoff reel 16 is charged into the heating zone 11 of the continuous annealing furnace. At this time,
In the annealing furnace, the burner is controlled based on actual operating conditions to gradually increase the temperature of the steel plate 17. Now, for example, a steel plate 17 with a width of 1200 am and a thickness of 0.75 jw+ is charged into the heating zone 11 at a speed of 120 m/sin, fuel is supplied and the burner is controlled, and the temperature of the steel plate 17 is set to 700 m/sin as shown in FIG.
The temperature is gradually increased from ℃ to 2.5℃/win (as shown in FIG. 4). At this time, as shown in FIG. 17
The temperature is measured by the temperature sensor 32. 33 is a linearization circuit. Therefore, the steel plate 17 that is measured and output by the sensor 32 and the linearization circuit 33
temperature increases gradually, and the change in temperature increase rate is the third
As shown in the figure, it remains almost constant. And the steel plate temperature is 7
When the temperature reaches 20°C, the change in the rate of temperature increase slows down and reaches the so-called transformation point (+ wet n'J) of the steel plate 17.The temperature of the radiation thermometer 19 at this time is determined by hypothetically adjusting the correction setting value as described above. 1, for example, 730°C without indicating the transformation point temperature of 720°C.
If the temperature is indicated as 'C', if you use the setting dial etc. of the correction setting section 31 to output an output S corresponding to 720 degrees Celsius, the setting dial value at that time and the setting dial value of the setting section 31. The output can be defined as the emissivity setpoint. Then, this emissivity correction value is applied to the correction setting section 3.
The true temperature of the steel plate 17 can be measured by outputting it as a correction setting value from 1 and correcting the measured temperature of the steel plate as a correction value using the emissivity correction circuit 34 or the like.

Therefore, according to the embodiments described above, the transformation point temperature, which is the true temperature uniquely determined by the composition of the steel plate 17, is used, and the temperature of the steel plate 17 is raised according to the actual operating conditions in an actual furnace to reach the transformation point. Since the emissivity correction value is obtained by detecting the temperature, there is no need to create experimental equipment with the same conditions as the actual furnace as in the past, and the influence of the contact state with the moving steel plate 17, frictional heat, etc. There is no need to use a contact type thermometer such as a conventional furnace, and the true temperature of the steel plate 17 can be easily and accurately measured while the steel plate 17 is running in a normal actual furnace.

Note that the present invention is not limited to the above embodiments.

For example, in the above embodiment, an example of measurement was shown at the A2 transformation point temperature of iron, but it goes without saying that other transformation points may be used, and that the present invention can also be applied to other metals having transformation points.

Moreover, it is not limited to a continuous annealing furnace, and may be any other heating furnace or annealing furnace. Furthermore, this method can be used not only to determine the emissivity correction value of the radiodensitometer, but also to check for abnormalities in the measured values of the thermometer. In addition, the present invention can be implemented with various modifications without departing from the gist thereof.

〔Effect of the invention〕

As detailed above, according to the present invention, the transformation point temperature of the object to be measured is known, and the emissivity correction value of the radiation thermometer is obtained by utilizing this transformation point temperature and the actual operating conditions in the actual furnace. Therefore, the emissivity correction value can be accurately determined with a simple configuration without requiring special equipment or equipment, and the true temperature of the object to be measured can therefore be accurately determined.

[Brief explanation of drawings]

Figures 1 to 4 are for explaining an embodiment of the emissivity correction method for a radiation thermometer according to the present invention. Figure 1 is a diagram showing the relationship between iron temperature and specific heat, and Figure 2 is a continuous graph. Schematic diagram of an annealing furnace. The third factor is an explanatory diagram for detecting the transformation point temperature from the relationship between heating time and steel plate temperature. Figure 4 is a schematic diagram of a radiation thermometer. The fifth factor is contact temperature. FIG. 2 is an explanatory diagram of a conventional emissivity correction method using a meter. DESCRIPTION OF SYMBOLS 11... Heating zone, 12... Soaking zone, 17... Object to be measured (for example, steel plate), 19... Radiation thermometer, 31
. . . Correction value setting section, 34 . . . Emissivity correction circuit. Applicant's Representative Patent Attorney Takehiko Suzue

Claims (1)

[Claims] After knowing the transformation point temperature of the object to be measured in advance, the object to be measured is gradually heated in an actual furnace to find the part where the change in temperature increase rate slows down, and the temperature at this time and the transformation point temperature which is the true value are determined. An emissivity correction method for a radiation thermometer, characterized in that an emissivity correction value is obtained from the above and used as a correction set value for a measured temperature.