JPS5913924A - Method and apparatus for measuring surface temperature of steel material in horizontally moving type continuous heating furnace - Google Patents

Abstract

PURPOSE:To measure accurately a surface temperature by eliminating an error of backward noise, by moving a cylindrical sheltering body up and down for steel materials and using skillfully the difference in the measured value of radiation energy and the sheltering rate between the position of an ascending limit and that of a descending limit. CONSTITUTION:Outputs of a thermometer 4 at the time when a sheltering body 2 is placed at the position of an ascending limit and that of a descending limit, are denoted by Eu, Ed, the sheltering rates at this time are denoted by Ku, Kd and the calculated sheltering rates are denoted by Kou, Kod. The outputs Eu, Ed are read in an arithmetic device 20 by a detection signal from an ascending limit position detector 12 and a desending limit position detector 13. The thickness (t) of a steel material S placed just under the thermometer 4 from a computer 21 tracking the materials is read by the arithmetic device 20 and the rates Kou, Kod are calculated from the space H between the lower end face of the body 2 and the upper face of the material S and then, the surface temperature Ts of the material S is outputted by calculating on equation from the calculated rates Kou, Kod and an emissivity epsilons of the preliminary set up material S. E(Ts) is the output of the thermometer 4 at the time when the temperature of the body having 1.0 emissivity is Ts.

Description

[Detailed description of the invention] This relates to technology for measuring the surface temperature of materials.

For example, the problem with non-contact measurement of the surface temperature of steel using a radiation thermometer in a heating furnace where the steel is moved horizontally, such as a pushchair heating furnace or a rotary furnace, is that the radiant energy from the furnace wall is Radiant energy reflected by the surface of the heated steel material (hereinafter referred to as back noise)
This is the error caused by the radiation entering the radiation thermometer.

Conventionally, as a means to remove errors caused by this backward noise,
Broadly speaking, there are shielding methods and correction methods.

In the shielding method, as shown in FIG. 1, a cylindrical shield 2 is hung vertically from the ceiling 1a of the heating furnace 1, and a radiation thermometer 4 is installed at the upper end of the through hole 3 of the ceiling 1a and the cylindrical shield 2. , the cylindrical shielding body 2 shields the backward noise caused by the radiant energy from the furnace wall 1b being reflected by the surface of the heated steel material S, thereby reducing measurement errors.

However, under temperature measurement conditions on the heating zone entrance side of a continuous heating furnace where the temperature difference between the heated steel material S and the furnace wall 1b is 500°C or more, it is necessary to There are cases where a cylindrical shielding body 2 with a diameter larger than φ is required, which is difficult in practice.

On the other hand, the correction method is, for example, as shown in FIG.
A comparison body 5 having almost the same reflectance as the steel material S is installed inside the heating furnace 1, and a through hole 3 facing the position of the steel material S and a through hole 6 facing the position of the comparison body 5 are installed in the ceiling 1a of the heating furnace 1. and a radiation thermometer 4 is provided at the upper end of the through hole 3, and a radiation thermometer 7 is provided at the upper end of the trench through hole 6, so that the radiant energy radiated from the surface of the comparison body 5 is transmitted to the surface of the steel material S. The comparison body 5 is cooled so that it is negligibly small compared to the radiant energy radiated from the surface of the steel material S, and the radiant energy incident on the radiation thermometer 7 is reduced to only backward noise, and the surface of the steel material S measured by the radiation thermometer 4 is The temperature measurement value is corrected by the back noise measurement value obtained by the radiation thermometer 7 to accurately measure the surface temperature of the steel material S.

However, from Kotobuki, the difference in reflectance between steel material S and comparative material 5't 0
．． If the value is not within 0.01, the measurement accuracy will be poor and implementation will be extremely difficult.

The present invention solves the problems of the conventional methods and makes it possible to relatively easily and accurately measure the surface temperature of steel in a horizontally movable continuous heating furnace.

An example of the implementation of the present invention will be explained below based on FIGS. 3 and 4.

In FIG. 3, ] is a horizontally movable continuous heating furnace, and 2 is movable up and down from the through hole 1C in the ceiling 1a of the heating furnace 10 so that the lower end face faces the upper surface of the steel material S at a predetermined position in the heating furnace 1. A radiation thermometer 4 is provided at the upper end of the through hole 3 of the cylindrical shield 20 .

A connecting rod 8 is provided at the upper end of the cylindrical shielding body 2, and a hanging tool 9 is provided at the upper end of the connecting rod 8. A hanging tool 9 is connected to a driving means provided in, for example, a piston rod lla of an air cylinder 11.

That is, the cylindrical shield 2 is connected to an arbitrary structure above the heating furnace 1 through an air cylinder 11, a hanger 9, a connecting rod 8, and a through hole IC in the ceiling 1a of the heating furnace 1. It is vertically installed in the air cylinder 11 and is moved up and down by an air cylinder 11.

The air cylinder 11 has its piston rod l.
Detecting means, such as detectors 12 and 13, are provided to detect the upper limit position and lower limit position of la, respectively, and detect the upper limit position and lower limit position of the cylindrical shield 2.

Note that as a means for detecting the upper limit position and lower limit position of the cylindrical shield 2, for example, a touch lever is protruded from the connecting rod 8 of the cylindrical shield 2, and detection is carried out on an arm hanging vertically from the structure 10. Detectors 12 and 13 are provided above and below, and the detector 12 is closed via the touch lever at the upper limit position of the cylindrical shield 2, and the detector 13 is closed via the touch lever at the lower limit position of the cylindrical shield 2. You can do it like this.

Also, the piston rod iia of the air cylinder 11
The timing of vertical movement, that is, the timing of vertical movement of the cylindrical shield 2 may be synchronized with, for example, a forward movement completion signal of a pusher for moving the steel material S.

An arm 14 projecting laterally is provided at the upper end of the cylindrical shield 2, and a sealing skirt 15 surrounding the outer periphery of the cylindrical shield 2 is provided inside this arm 14. .

This sealing skirt 15 is inserted into a sealing water tank Id provided on the upper surface of the ceiling 1a, which is located at the through hole IC of the ceiling 1a of the heating furnace 1, to prevent the gas inside the furnace from leaking to the outside. ing.

An appropriate amount of water is supplied into the sealing tank 1d by a water supply pipe with a water level adjustable valve, and the water in the sealing tank 1d is discharged to the outside by an overflow pipe.

A guide roller 16 provided on the outside of the arm 14 is in contact with the outer periphery of the sealing water tank 1d, so that the cylindrical shield 2 can vertically move up and down to minimize lateral vibration.

The cylindrical shield 2 has a double water cooling circulation wall 2a on the inside, and a
The outer surface is a heated wall 2b, and a water supply pipe 17 and a drain pipe 18 are provided at each upper end of the double water cooling circulation wall 2a.

In this way, ml ? ! [Skid in position] A cylindrical shield 2 whose distance from the upper surface of the steel material S on 9 can be varied is installed.

Now, with respect to the steel material S, the shielding rate of backward noise from the reactor wall by the cylindrical shield 2 is different between the upper limit position and the lower limit position of the cylindrical shield 2, so the radiation The output of the thermometer 4 also changes.

Therefore, the output of the thermometer 4 when the shield 2 is at the upper limit position is Ell %, the shielding rate at this time is Kl, and the output of the thermometer 4 when the shield 2 is at the lower limit position is Ed.
The shielding rate at this time is Kd, and the surface temperature of the steel material S is TS
, if the emissivity of the steel material S is εS, and the backward noise is G, then E
ll and Ed are expressed by the following formula.

E u−ε5E(Ts) 10 KuG −・−・・
-(])Ed-ε5E(Ts)+KdG...
(2) However, E(TS) is the output of the thermometer 4 when the temperature of an object with an emissivity of 10 is TS.

The calculated shielding rate of the shielding body 2 can be calculated from the radiative heat transfer theory if the conditions that the surface of the steel material S is a perfect diffusive surface and that the shielding body 2 is a perfect absorber and there is no radiation from the shielding body 2 are established. It is expressed as in equation (3).

Ko = m”/ (1+rr?)
--.'' (3) However, it is m-1 insects, ■ is the distance between the lower end surface of the shielding body 2 and the second surface of the steel material S, and R is the radius of the shielding body 2.

However, in reality, the above conditions are not completely satisfied, so the true shielding rate is K. It is expressed as follows using .

K-αK O (4) However, α is a constant determined by the degree of deviation from the above conditions.

From the relationship in equation (4), the shielding body Ku at the upper limit position of the shielding body 2 and the shielding rate Kd at the lowering limit position are as follows.

Ku-α・K, u・・・・・・
・・・・・・・・・(5) Kd−α・KOd
・・・・・・・・・・・・・・・(6)(5)
Substituting equation (1) into equation (1) and equation (6) into equation (2) yields the following.

Eu-ε5E(Ts)+α・Kou-G...
・・・・・・・・・・・・(7) Ed−εBE(T8)
+α・Kod−G ・・・・・・・・・・・・・・・
...(8) And (force formula x d - (8) If G is deleted from the formula XKou, E(Ts) becomes as follows.

E(TS) = (Ko d-E to hold u ・Ed)/
(εS (Kod−Kou) ) ・”(9) Therefore, the emissivity of the steel material S εS1 Calculated shielding rate K at the upper limit position of the shielding body 2 U, Calculated shielding rate at the lower limit position ■
6d, the surface temperature Ts of the steel material S can be determined from the output Eu of the thermometer 4 at the upper limit position of the shield 2 and the output Ed of the thermometer 4 at the lower limit position.

Note that the emissivity εS of the steel material S is determined in advance off-line.

In addition, during the measurement, the shielding body 2 was cooled with water to
Cool to 0°C.

Therefore, an example of the means for measuring the surface temperature of the steel material S is the fourth
As shown in the figure, the output E of the thermometer 4 is determined by the detection signal from the detector 12 when the shield 2 reaches the upper limit position.
u is read into the arithmetic unit 20, and the detection signal from the detector 13 when the shielding body 2 reaches the lowering limit position,
The output Ed of the thermometer 4 is read into the computing unit 20.

The calculator 20 also reads the thickness of the steel material S located directly below the thermometer 4 from the computer 21 that tracks the steel material S.

Furthermore, the calculator side subtracts the thickness L of the steel material S from the distance between the upper surface 1.9a of the skid 19 and the lower end surface of the shield 2, and calculates the distance between the lower end surface of the shield 2 and the upper surface of the steel material S. Calculate the calculated shielding rates Kou and Kod from H, and add u, Knd, and the output value of the altimeter 4 1 (:l) to the calculated shielding rate of
, Ed and the emissivity εS of the steel material S preset on the computer side, the calculation of equation (9) is performed to output the surface temperature TS of the steel material S.

As described above, the present invention moves a cylindrical shield up and down relative to the steel material whose temperature is to be measured in a heating furnace, and measures radiant energy at the upper limit position and lower limit position of the cylindrical shield. This is a new correction method that skillfully uses the difference in the shielding rate and the shielding rate. Even if it is installed so that it is about 330 ynm, it is possible to eliminate the error due to backward noise, and therefore it is possible to accurately measure the surface temperature of the steel material in the horizontally movable continuous heating furnace.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a conventional shielding method, Fig. 2 is a schematic diagram showing an example of a conventional correction method, Fig. 3 is a schematic diagram showing an example of implementation of the present invention, and Fig. 4 is a block diagram of calculation. It is. (11) Figure 1 Figure 2 (12)

Claims (2)

[Claims] (1) At a predetermined position of the steel material being moved horizontally on the Sugirad in the heating furnace, move the cylindrical shield having a radiation thermometer at both ends up and down, and set the upper limit position of the cylindrical shield. In addition to measuring the radiant energy from the steel material through the cylindrical shield at the lower limit position and the lower limit position, the shielding rate of the radiant energy from the furnace wall by the cylindrical shield at the upper limit position and lower limit position of the cylindrical shield is measured. A method for measuring the surface temperature of a steel material in a horizontally movable continuous heating furnace, characterized in that the surface temperature of the steel material is determined from each of the calculated shielding ratio values and each of the measured radiant energy values. (2) A cylindrical shield having a radiation thermometer at its upper end, which is vertically movable from a through hole in the ceiling of the heating furnace so that its lower end faces the upper surface of the steel material at a predetermined position in the heating furnace; a driving means for vertically moving the cylindrical shield; a rising limit position detecting means for detecting a rising limit position of the cylindrical shield; a lowering limit position detecting means for detecting a lowering limit position of the cylindrical shield; According to the ascent limit position detection signal and the descending limit position detection signal of the body, each measurement value of the radiant energy from the steel material measured by the radiation thermometer through the cylindrical shield is read, and the radiant energy from the furnace wall by the cylindrical shield is read. Measuring the surface temperature of steel in a horizontally movable continuous heating furnace, comprising calculation means for calculating each shielding rate of radiant energy and calculating the surface temperature of the steel based on each calculated shielding rate and each measured value of radiant energy. Device.