JPS584973B2 - Method for estimating internal temperature of hot steel ingot - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for easily estimating the internal temperature of a hot steel ingot or billet heated in a soaking furnace or heating furnace without coming into contact with the steel ingot.

The internal temperature of a heated steel ingot is an important factor in predicting the baking of the steel ingot in the blooming soaking furnace necessary for rolling, and in other rolling processes, so it is necessary to understand it. Conventionally, the internal temperature of these hot steel ingots has been predicted based on the thermal conductivity of the material, the heating temperature and time in a soaking furnace, the cooling time after mold cutting, etc.

Therefore, it is just an estimated prediction, and it has a considerable error in comparison with the actual internal temperature.

In addition, with the development of various thermometers, it is now possible to easily measure the temperature on the surface of a steel ingot, so methods have been used to substitute the internal temperature with the surface temperature, or to estimate the internal temperature from the surface temperature, but both methods are accurate. Therefore, it has been difficult to accurately estimate the internal temperature in a non-destructive manner.

As a means to solve such problems, Japanese Patent Application No. 107142/1983 and Japanese Patent Application No. 1983 filed by the same applicant
There is a ``Method for estimating the internal temperature of a hot steel ingot'' in No. 107143.

The present invention relates to an internal temperature estimation method developed in connection with this prior art.

A feature of the present invention is that as a method for estimating the internal temperature without contacting the hot steel ingot, a model steel ingot is prepared in advance, a measurement hole is drilled from the outer surface to the inner center of the ingot, and the model A steel ingot is heated and soaked in a soaking furnace to form a hot steel ingot, which is carried out of the furnace, and a temperature measuring tool is inserted into the measurement hole to measure the internal temperature, and the outside of the hot steel ingot is measured. A flame is blown onto a certain point in the center of the surface to create a constant temperature, that is, a high-temperature area higher than the temperature of the material to be measured, and the falling temperature change in the high-temperature area is read to determine the temperature for several types of internally measured temperatures of the hot steel ingot. After creating a trend diagram of the change, the above-mentioned flame was applied to a part of the surface of the steel ingot to be measured, without measuring the internal temperature of the hot steel ingot each time. The internal temperature of the heated steel ingot is estimated by comparing the temperature change from a constant temperature during spraying with a trend diagram.

Hereinafter, embodiments of the method of the present invention will be described in detail.

In carrying out the present invention, a model steel ingot 1 is prepared as shown in FIG. 1, and an internal temperature measuring hole 2 is bored from the center of the outer surface of the model steel ingot to the center of the inside of the steel ingot.

Next, this model steel ingot 1 is charged into a soaking furnace and heated and soaked to a predetermined temperature to form a hot steel ingot, which is then carried out of the furnace.

Next, immediately outside the furnace, an internal temperature measuring device 3 such as a thermocouple is inserted into the internal temperature measuring hole 2 to measure and record the internal center temperature of the hot steel ingot 1.

Here, a flame blowing nozzle 4 as shown in FIG. 2 is brought close to one location on the outer surface of the hot steel ingot 1, and a flame is blown using, for example, oxygen, acetylene, C gas, combustion air, etc. as fuel. Add and heat partially.

At this time, the flame spraying point is located at the third point due to the temperature difference with the hot steel ingot surface.
As shown in the figure, the highest temperature part 11 is formed at the center of the heating point,
A concentric pattern with a temperature difference is created around this point.

This highest temperature part 11 is measured using, for example, a radiation thermometer,
Spraying is stopped when the temperature of the hottest part reaches a certain temperature, for example 1300°C.

The reason why the temperature for spraying was set at 1300℃ is because the soaking temperature of steel ingots is usually 1200 to 1250℃, so if the temperature is lower than this temperature, the temperature change in the highest temperature part of spraying (the center of spraying) This is because the temperature is preferably higher than the soaking temperature because it is difficult to recognize the appearance of heat.

At this time, the highest temperature section 11 is influenced by heat from inside the hot steel ingot, and then the temperature change in the highest temperature section 11 within a short time is measured with a radiation thermometer, and this is compared with the above-mentioned diagram. By finding matching temperature curves, the internal temperature of a hot steel ingot can be determined in a short time.

In carrying out the present invention, a temperature change diagram is created using model steel ingots for each steel ingot and steel slab for each size, and depending on the dimensions of the actual steel ingot, the various model steel ingots, steel It is sufficient to carry out the comparison using a diagram corresponding to the piece.

According to the present invention, since the temperature change obtained is based on the results of actual measurements using a model steel ingot, the internal temperature that is closest to the actual measurement value and has the least error can be obtained without contact and in a short time. can.

Therefore, it is possible to estimate the internal temperature of the steel ingot before it is charged into the soaking furnace during the blooming process, thereby achieving the desired high-accuracy baked clay without overheating or underburning. It can be tightened.

In addition, by understanding the internal temperature of a hot steel ingot, effective information can be obtained in the hot rolling process, which improves rolling accuracy and quality, making it possible to save fuel and make effective use of furnaces.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a model steel ingot during internal temperature measurement. FIG. 2 is an explanatory side view showing the state of flame spraying on a hot steel ingot. FIG. 3 is a front view of a heated steel ingot with a temperature difference pattern formed in the sprayed parts. 1: Model steel ingot, 2: Internal temperature measuring hole, 3: Internal temperature measuring device, 4: Nozzle for flame spray.

Claims (1)

[Claims] 1. Preparing in advance a model steel ingot with holes for internal temperature measurement drilled from the outer surface toward the center of the interior, heating and soaking the model steel ingot in a soaking furnace to obtain a hot steel ingot;
Carrying the heated and soaked model steel ingot out of the furnace and inserting an internal temperature measuring device into the measurement hole to measure the internal temperature of the heated steel ingot; A flame is sprayed onto one spot on the outside surface to create the highest temperature part with a predetermined temperature higher than that of the material to be measured, and once the highest temperature part reaches the predetermined temperature, the flame spray is stopped and the inside of the hot steel ingot is heated. Measure the falling temperature change of the highest temperature part in correspondence with the temperature, and obtain the actual measured value of the falling temperature change of the high temperature part with respect to the internally measured temperature by changing several heating temperature conditions of the model steel ingot. After that, when measuring the temperature of a hot steel ingot for practical use, blow a flame onto the outer surface of the hot steel ingot without measuring the internal temperature, and measure the highest temperature part under the same conditions as the above-mentioned highest temperature part. Capturing only the decreasing temperature change of the highest temperature part,
The interior of a thermal steel ingot is characterized in that the obtained tendency of temperature change is compared with a diagram obtained using a model steel ingot, and a temperature curve that matches this is obtained to estimate the internal temperature of the practical thermal steel ingot. Temperature estimation method.