JPS6213526A - Method for controlling temperature of induction heating furnace - Google Patents

Abstract

PURPOSE:To decrease temp. gradient and variance in width direction, by detecting temp. distribution in width direction of material to be heated such as slab, measuring temp. difference in width direction in process from extraction from induction heating furnace to finish rolling mill being the most point on rolling, and controlling temp. due to these informations. CONSTITUTION:Material to be heated such as slab heated by heating furnace is further heated to high temp. by induction heating furnace providing computer for controlling temp., then hot rolled. Thereat, temp. distribution in width direction of slab before being charged into induction heating furnace is detected. From the information, feed foreward function of computer for correcting setting conditions of fed electric power and time in width direction, or temp. in width direction from extraction from induction heating furnace to finish rolling side is measured. From the information of the temp. distribution, temp. is controlled by controlling computer providing feed back function for correcting fed power and time in width direction of computer.

Description

[Detailed Description of the Invention] <Object of the Invention> Industrial Application Field The present invention relates to a temperature control method for an induction heating furnace.
The present invention relates to a temperature control method for an induction heating furnace in which a slab heated in a heating furnace is further heated at a high temperature in an induction heating furnace.

Conventional technology When induction heating a slab or the like, a method is usually adopted in which the input power is varied multiple times during the heating process.

Also, by dividing the coil into several blocks and changing the input power for each block, "JArf!" in the slab width direction can be adjusted.
, methods have also been taken to make the distribution uniform.

In order to automate this method, information about the material to be heated, such as the dimensions of the material to be heated, such as a slab, is given to the computer before heating, and the computer uses this information to calculate the heating time, input power, required amount of capacitor a, etc. A method has been proposed in which the setting conditions for each device are solicited, automatic settings are made based on the needle ring results, and then instructions are given to open/close and adjust the power supply to heat the material to be heated to a predetermined temperature. Publication No. 49-64938).

However, this method involves changing the applied power in the width direction of the material to be heated, such as a slab, and cannot be said to essentially improve the method of controlling the temperature of the material to be heated, such as a slab.

Another problem is that the input power is open-loop and does not include correction logic such as a learning function.

Generally, in the process of hot rolling a material to be heated such as a slab after induction heating, the heating method often affects the quality of the steel strip coil and the ease of rolling. A method has been adopted in which a temperature sensor is provided for each block of heating coils to make the temperature distribution uniform in the width direction of a material to be heated such as a slab.

However, with this method, scale floats up while the material to be heated such as a slab is being heated, making it impossible to measure the true temperature, making it impossible to perform the function of the temperature sensor, and making it impossible to achieve sufficient temperature control.

Problems to be Solved by the Invention The present invention aims to solve these problems,
Specifically, the temperature distribution in the width direction of the material to be heated such as a slab can be detected more accurately, and the temperature distribution in the width direction can be detected at a certain point in the process from induction heating furnace extraction to the finishing rolling mill side, where the top edge of the rolling is also a key point. It is an object of the present invention to provide a temperature control method for an induction heating furnace, which comprises measuring temperature differences and providing this information to a bullet measuring device to set operating conditions for the induction heating furnace.

<Structure of the Invention> Means for Solving the Problems and Their Effects That is, the present invention provides a method for controlling the temperature of a material to be heated such as a slab heated in a heating furnace. When hot-rolling the heated material after heating it to a high temperature using the induction heating furnace equipped with the induction heating furnace, the temperature distribution in the width direction of the slab before it is charged into the induction heating furnace is detected, and from that information, the A feedforward function that corrects the width direction input power and time setting conditions and/or a thermometer installed in the width direction between the extraction of the induction heating furnace and the finish rolling side,
The present invention is characterized in that it is equipped with a feedback function for correcting the input power and time in the width direction of the bullet measuring machine based on the information on the temperature distribution, thereby controlling the temperature.

Hereinafter, the structure and operation of the present invention will be explained with reference to the drawings.

Figure 1 is an explanatory diagram of a system that performs feedforward and feedback control using information on the widthwise temperature distribution of the material to be heated in induction heating equipment. Figure 2 is an explanatory diagram of an induction heating furnace that can change the input power in the widthwise direction. , Figure 3 is an explanatory diagram of a closed-loop temperature control device using a temperature sensor installed in an induction heating furnace.
FIG. 4 is a graph showing the temperature distribution in the width direction on the finishing rolling exit side.

The present invention describes a method for accurately controlling the temperature of induction heating in the process of hot rolling after induction heating a slab. The induction heating equipment used in the present invention is as shown in Fig. 2. , multiple pieces in the slab width direction (
The figure shows three cases. ), the heating coil is divided into blocks, and each block is equipped with three input power equipment (see 7.8.9), and has the function of changing the input power to change the temperature in the width direction of the slab. This is how it was done.

Normally, temperature sensors (e.g., radiation thermometers) are installed at several locations in each block or in the slab width (a direction) or length direction (b direction) to measure the temperature, as shown in Figure 3. The input power of each block is controlled.

However, this method using a temperature sensor is subjected to considerable disturbance due to scale generated on the surface of the slab during heating, causing considerable variation in the measured temperature values, so that it can only serve as a monitor.

In the present invention, in addition to control using such a temperature sensor, as shown in FIG. Information from a temperature sensor capable of measuring temperature is given to the control calculation line, and based on this information, the temperature correction amount in the slab width direction (ΔXi℃) is determined and reflected in the heating of the rolled material such as the next slab. It has a feedback function to By doing so, it is possible to prevent the influence of the scale of the slab, and it is also possible to prevent troubles such as bending of the material to be rolled during rolling.

Furthermore, in the case of obtaining temperature distribution information in the direction 1 before heating in an induction heating furnace, the present invention uses the above-mentioned feedback function as well as correction (△Yi℃) based on the temperature distribution in the width direction of the slab before charging. It has a feedforward function that adds , and it is possible to set the temperature distribution in the middle direction of the rolled material at any point in the rolling process by using either or both of the above two functions. It is.

Example This will be further explained below with reference to Examples.

Example 1 Slab for hot rolling (slab size: 250mm thick x 10
008 width x 110,000 iI length) was heated in a gas heating furnace to an average temperature of 1180°C, and then heated in an induction heating furnace to an average temperature of 1350°C using a computer with a feedback function shown in FIG. 1 to perform hot rolling. For comparison, a case where the temperature was controlled only with a temperature sensor installed in the induction heating furnace was recorded using a width direction temperature sensor installed on the finishing rolling exit side. The results are shown in FIG. According to this, it can be seen that a temperature gradient is generated in the width direction.

In the actual results of 100 coils, the value of (a-b)-c ['C] is, in the case of the present invention, average c--5℃, standard deviation σ-1
In the case of the comparative example, the average temperature was τ-10°C and the standard deviation σ-15°C.

This clearly shows that the present invention was effective.

Example 2゜Hot rolling slab (slab size: 300111ff
1 thickness x 1100s width x 1000011111 length) was heated in a gas heating furnace to an average temperature of 1150℃, and then
An average temperature of 1350 in an induction heating furnace was determined by a computer with feedforward and feedback functions as shown in the figure.
It was heated to ℃ and hot rolled. At this time, we measured the temperature distribution in the width direction of the slab ΔYi = 15°C before charging into the induction heating furnace, and the temperature distribution in the width direction of the slab after extraction from the induction heating furnace ΔX1 = 30°C, so we similarly induced the same slab size of the next material. This was corrected when heating.

The results are shown in comparison between before the feedback and feedforward functions were introduced (Fig. 5 (A)) and after (Fig. 5 (B)). According to this, the improvement is about 20°C, with an average τ = -3°C and a standard deviation σ = 7°C, and in the case of the comparative example, an average c = -10°C and an eft standard deviation σ -15°C.
Met.

<Effects of the Invention> As explained above, the present invention has a feedforward function that detects the temperature distribution in the middle direction of the slab before it is charged into the induction heating furnace, and corrects the width direction input power and time setting conditions from that information. and/or a control computer with a feedback function that measures the temperature in the width direction from induction heating furnace extraction to the finish rolling side and corrects the input power and time in the width direction of the computer from information on the temperature distribution. A temperature control method for an induction heating furnace, which is characterized in that the temperature is controlled at Problems such as bending can be prevented, and the temperature gradient and its dispersion in the width direction are reduced.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a system that uses the width direction temperature distribution information of the heated material before and after induction heating, and further performs feedforward and feedback control. Figure 2 is an illustration of an induction heating furnace that can change the input power in the width direction. An explanatory diagram, Fig. 3 is an explanatory diagram of a closed-loop temperature control device using a temperature sensor installed in an induction heating furnace, Fig. 4 is a graph showing the width direction temperature distribution when a slab is heated in an induction heating furnace, and Fig. 5 ( A) and (B)
The following shows the results when a slab is heated in an induction heating furnace without a mum control function and when a slab is heated with a feedback function and a feedforward function.

Claims (1)

[Claims] The material to be heated such as a slab heated in the heating furnace is further heated to a high temperature by an induction heating furnace equipped with a temperature control computer, and when the material to be heated is hot rolled, the induction heating furnace equipment A feedforward function that detects the temperature distribution in the width direction of the slab before rolling and corrects the setting conditions of the input power and time in the width direction of the computer from that information and/or A temperature control method for an induction heating furnace, characterized in that the temperature is controlled by a control computer equipped with a feedback function that measures the temperature in the width direction and corrects the input power and time in the width direction of the computer from information on the temperature distribution. .